
Reinforced Concrete Terminal Warehouse—Baltimore and Ohio Railroad, New York 
M. A. Long, Engineer Turner Construction Company, Contractors 


Reinforced Concrete 
in Factory Construction 


The Atlas Portland Cement Company 

New York Chicago 


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■ H 




























































































Reinforced Concrete 
in Factory Construction 


'‘Concrete for 
Permanence” 


The Atlas Portland Cement Company 

30 Broad Street, New York Corn Exchange Bank Bldg., Chicago 

Philadelphia Boston St. Louis Minneapolis Des Moines Dayton Savannah 












Copyright by 

The Atlas Portland Cement Compant 
1907, 1912, 1913, 1914, 1915, 191S 
All rights reserved. 

Ninth Edition 



MN 151918 ^ 

'©CI.A‘399356 


'K-O \ 


INTRODUCTION 


T) EINFORCED concrete has provided for the manufacturer an en- 
tirely new building material. Indestructible, economical and fire¬ 
proof, it offers under most conditions features of advantage over every 
other type of construction. The development has naturally been great¬ 
est in the larger centers of population, but it is extending rapidly to the 
remoter districts, and, indeed, wherever new buildings are contem¬ 
plated. 

This widespread interest demands an authoritative treatment, and 
The Atlas Portland Cement Company has embraced this opportunity to 
present to the manufacturer, and also to the architect and the engineer 
who are not concrete specialists, a brief treatise on reinforced concrete 
for factory construction, with a view of giving a comprehensive idea of 
the advantages and limitations of the material as adapted to the factory, 
and a demonstration of its value as illustrated in a variety of buildings 
in different localities. 

The work has been prepared by a consulting engineer, Mr. Sanford 
E. Thompson, who is well qualified to treat the subject as an expert 
authority. The Atlas Portland Cement Company, occupying, as it does, 
a somewhat unique position among cement manufacturers, with its wide 
reputation for a thoroughly uniform and standard product, its selection 
by the United States government to furnish over 7,500,000 barrels for use 
in building the Panama Canal, and its immense production—over 50,000 
barrels per day—commends the book to its readers with the hope that it 
may prove a fitting companion volume to the other publications of the 
company. 


THE ATLAS PORTLAND CEMENT COMPANY. 



TABLE OF 


CHAPTER I.—FACTORY CONSTRUCTION. 7 

Safety of Reinforced Concrete Construction. 7 

Durability . 8 

Fire Resistance . 8 

Insurance . 9 

Stiffness . 9 

Freedom from Vibration. 9 

Versatility of Design. 9 

Light.. 9 

Watertightness . 9 

Cleanliness .1. 10 

Rapidity of Construction. 10 

Hanging Shafting . 10 

Roof . 10 

Tanks . 10 

Letting the Contract. 10 

Growth of Reinforced Concrete Construction. ... 10 

Appendix: Fire Insurance on Factories of Rein¬ 
forced Concrete. By L. H. Kunhardt. 11 

CHAPTER II.—DESIGN AND CONSTRUCTION. 13 

Cement . 13 

Sand . 13 

Specifications for Aggregates. 13 

Reinforcing Steel . 14 

Proportions of Materials. 14 

Consistency . 14 

Placing . 15 

Surfaces . 15 

Forms . 15 

Foundations. 15 

Basement Floor . 16 

Design of Floor System. 17 

Columns . 20 

Walls. 21 

Roofs. 21 

Construction . 21 

CHAPTER III.—CONCRETE AGGREGATES. ... 22 

Effect of Different Aggregates upon the Strength 

of Mortar and Concrete.. 22 

General Principles for Selecting Stone. 22 

Comparative Values of Different Stone. 23 

General Principles for Selecting Sand. 23 

Testing Sand. 25 

Testing Concrete Aggregates. 26 

Proportioning Concrete. 26 

PLANT OF CARTER’S INK COMPANY. 27 

Exterior Design . 27 

Reinforced Concrete Design . 28 

Foundations . 28 

Cost. 29 

KETTERLINUS BUILDING . 30 

Design .;. 30 

Columns . 31 

Floor System . 32 

Walls . 33 

Roof. 34 

Cost. 34 

Insurance. 34 

MAVERICK COTTON MILLS. 35 

Spinning Mill . 36 

Weave Shed . 37 

Power House . 38 

LYNN STORAGE WAREHOUSE. 39 

Floor Construction . 39 

Floor Specifications. 40 

Columns . 41 


CONTENTS 


WINCHESTER REPEATING ARMS FACTORY. . 43 

Design. 43 

Cost . 44 

BULLOCK ELECTRIC MACHINE SHOP. 45 

Design. 46 

Columns . 46 

Crane Brackets . 47 

Floor System. 47 

Walls. 48 

HUNTER ILLUMINATED CAR SIGN CO. FAC¬ 
TORY . 49 

Design . 49 

Construction . 49 

Cost . 50 

WHOLESALE MERCHANTS’ WAREHOUSE.... 51 

Layout . 51 

Beams and Slabs. 52 

Columns . 53 

Coal Trestle . 53 

Cost. 53 

PLANT OF BOSTON WOVEN HOSE & RUBBER 

CO. 54 

Design . 54 

Reinforced Concrete Piles. 55 

Construction . 56 

BUSH MODEL FACTORY. 57 

Design . 57 

Columns . 58 

Floor System . 59 

Construction . 60 

PACKARD MOTOR CAR FACTORY. 62 

Floor System. 63 

Columns . 64 

SYRACUSE COLD STORAGE CO. WAREHOUSE 66 

Design. 66 

Construction . 66 

Cost. 68 

BLACKSMITH AND BOILER SHOP OF THE 

ATLAS PORTLAND CEMENT CO. 69 

Design. 69 

Construction . 69 

PIERCE-ARROW MOTOR CAR FACTORY. 72 

Manufacturing Building. 72 

Assembly Building. 72 

Body Building. 73 

Storage and Nickel-Plating Building. 73 

Garage . 73 

Power House. 75 

PACIFIC COAST BORAX REFINERY. 76 

Design. 78 

Construction . 79 

The Fire . 79 

CHAPTER IV.—DETAILS OF CONSTRUCTION. 82 

Systems of Reinforcement. 82 

Concrete Block Walls. 86 

Concrete Tile. 86 

Surface Finish . 86 

Concrete Pile Foundations. 88 

INDUSTRIAL PLANT ROADWAYS. 94 

Construction Details . 94 

Plants Using Concrete Roadways. 94 





















































































































PREFACE TO NINTH EDITION 


The ninth edition presents substantially the 
same subject matter covered in the preceding 
edition, but the text has been condensed by elimi¬ 
nating some of the purely descriptive parts. 

Some new illustrations have been added to 
show the marked advance which has been made 
in improving the appearance of reinforced con¬ 
crete industrial buildings. The modern concrete 
factory needs no apologies on the score of ap¬ 
pearance when compared with factories of any 
other type of construction. 

To the chapter on concrete aggregates has 
been added the recently developed Colorimetric 
Test for organic impurities in sand. The neces¬ 
sity for a simple, reliable test for determin¬ 
ing the quality of sand for concrete has 
been long recognized by engineers. It is hoped 


that this test is one step toward this end. 

The chapter on design and construction has 
been left practically unchanged. The basic prin¬ 
ciples and methods of design have remained un¬ 
altered since the text was written. Perhaps the 
most marked tendency has been the increased 
use of flat-slab floor construction, without gird¬ 
ers and beams, one type of which was em¬ 
ployed in the Winchester Repeating Arms Fac¬ 
tory; described on page 43. The added head 
room and increase of light as well as simplicity 
of construction explain the increased adoption 
of this type of floor system. 

SANFORD E. THOMPSON, 

Maj. Ord. R. C., Washington, D. C. 
May 22, 1918. 


QUOTATION FROM PREFACE TO PREVIOUS EDITION 


The second* edition aims to cover the develop¬ 
ments in the field of reinforced concrete as ap¬ 
plied to factory construction since the appear¬ 
ance in 1907 of the first edition. 

As in the previous issue, details are presented 
of this type of construction and a careful de¬ 
scription, with numerous illustrative drawings 
and photographs, is given of typical examples of 
concrete buildings selected from various sections 
of the country and erected by representative 
builders. Suggestions are thus offered to the 
factory owner who contemplates building in 
reinforced concrete, while at the same time the 
practical details may prove of value to archi¬ 
tects, engineers and builders. 

The chapter on Design and Construction has 
been rewritten, the chapter on Details of Con¬ 
struction has been revised and new articles have 
been added, describing in detail different types 
of factories that have been built of reinforced 
concrete during the interval that has elapsed 
since the issue of the first edition. 

The large increase in the quantity of material 
has necessitated a rearrangement of the text and 
renumbering the pages. 

The first chapter presents to the manufac¬ 
turer a brief review of the qualities of reinforced 
concrete in comparison with other materials for 
factory buildings, and this is followed by a chap¬ 
ter giving in considerable detail the general prin¬ 
ciples of design with information in regard to 


methods of construction. Chapter III treats of 
the selection of the aggregates. These general 
chapters are followed by a number of articles 
describing in full some one shop, factory or ware¬ 
house of reinforced concrete, selected with a view 
of presenting a variety of the more usual types 
of factory and warehouse construction. 

Chapter IV outlines with illustrations many 
of the styles and systems of reinforcement in 
common use in building construction, and briefly 
refers to examples of concrete block walls, sur¬ 
face finish, concrete pile foundations and tanks, 
each illustrated by photographs. 

All illustrations, excepting a part of those in 
Chapter IV, have been prepared especially for 
this book. The half-tones are made from orig¬ 
inal photographs, and the designs from drawings 
furnished by the engineers and contractors, or 
reproduced in the office of the author from the 
original plans. In this way a number of details 
are shown which seldom appear in print. Care 
has been taken throughout to give complete 
measurements so that the figures may be used as 
a guide to new construction work. 

The Atlas Portland Cement Company, and the 
undersigned, desire to express their appreciation 
of the courtesies extended by individuals and 
companies who have kindly furnished plans and 
data for incorporation into the descriptive 
chapters. 

SANFORD E. THOMPSON, 
Newton Highlands, Mass. 


1913 Reprint of Second Edition. 


March 1, 1912. 






Hoboken Land & Improvement Company, Hoboken, N. J. 
Charles Fall, Architect. Turner Construction Company, Contractors 



































































CHAPTER I—FACTORY CONSTRUCTION 


A manufacturer about to build a factory or 
warehouse must choose between several types 
of construction. In this selection the governing 
considerations are cost, safety, durability, and 
fire protection, while many minor factors enter 
into each individual case. 

In this opening chapter the qualities of the 
different materials available for factories are dis¬ 
cussed with special reference to the reinforced 
concrete. 

Types of buildings for mills, factories, and 
warehouses may be classified as follows: 

(1) Frame construction; 

(2) Steel construction; 

(3) Mill or slow burning construction; 

(4) Reinforced concrete construction. 

The first and cheapest type of frame construc¬ 
tion may be neglected as unsuitable for per¬ 
manent installation because of its lack of durabil¬ 
ity and its fire risk. Board walls, narrow floor 
joists, board floors and roofs, not only do not 
protect against fire, but in themselves afford fuel 
even when the contents of a factory are not com¬ 
bustible. 

Steel construction with concrete or tile floors, 
provided the steel is itself protected from fire 
by concrete or tile, is efficient and durable, but 
its first cost alone will usually prohibit its use for 
the ordinary factory building. 

Mill, or “slow burning” construction, as it is 
sometimes called to distinguish it ffom fireproof 
construction, consists of brick, stone, or concrete 
walls, with wooden columns, timber floor beams 
and thick plank floors, which, although not fire¬ 
proof, are all so heavy as to retard the progress 
of a fire and thus afford a measure of protection. 

Reinforced concrete for factories and ware¬ 
houses, and also for office buildings, hotels, and 
apartment houses, as compared with steel is 
lower in cost, requires less time to build, and has 
a greater freedom from vibration. 

As compared with slow burning construction, 
reinforced concrete gives greater fire protection, 
with less maintenance costs because of lower in¬ 
surance rates, durability, freedom from repairs 
and renewals, and in many cases with even lower 
first cost. 

COST. - 

As a fundamental principle in mill and factory 
construction, the cost must be such that the out¬ 


lay for interest on construction, running ex¬ 
penses, and maintenance, shall be at the lowest 
possible minimum consistent with conservative 
design and the requirements of operation. A 
wooden building is cheap in first cost, and there¬ 
fore in interest charges, but is expensive in in¬ 
surance and repairs, while the risk of the loss in 
production after a fire, for which no insurance 
provides, may far counterbalance any theoretical 
saving. 

As a general proposition, reinforced concrete 
is almost invariably the lowest priced fireproof 
material suitable for factory construction. The 
cost is nearly always lower than that for brick 
and tile, and with lumber at a high price it is 
frequently even lower than brick and timber, 
with the added advantage of durability and fire 
protection. 

In comparing the cost of different building 
materials, one must bear in mind that the con¬ 
crete portion of the building is only a part of 
the total cost. Since the cost of the finish and 
trim may equal or exceed that of the bare struc¬ 
ture, even if the concrete itself cost, say, 10 per 
cent, more than brick and timber, the cost of the 
building complete may not be 5 per cent, greater 
than with timber interior. The lower insurance 
rates will partly offset this even if there is no 
other economical advantage for the fireproof 
structure. 

The exact cost of a building in any case is gov¬ 
erned by local conditions. In reinforced con¬ 
crete the design, the loading for which it must 
be adapted, the price of cement, the cost of ob¬ 
taining suitable sand and broken stone or gravel, 
the price of lumber for forms, the wages of the 
laborers and carpenters, are all factors entering 
into the estimate. Reinforced concrete is largely 
laid by common labor, so that high rates for 
skilled laborers affect it less than any of the 
other building materials. 

SAFETY OF REINFORCED CONCRETE 
CONSTRUCTION. 

It is as important for reinforced concrete 
buildings as for other types that the designer 
be competent, and that the builder be of un¬ 
doubted experience and with a knowledge of the 
fundamental principles of this particular type of 
construction. By this it is not meant that the 
builder be an expert mathematician, but he 


7 


should be able to recognize the necessity for plac¬ 
ing the steel near the bottom surface of the 
beams and slabs, of accurately placing all the 
steel exactly as called for on the plans, uniform 
proportioning of the concrete, of breaking joints 
at the proper places, of laying beams and slabs 
as a monolithic floor system, and of determining 
the hardness of the concrete before removing 
forms and shores. 

The safety of a well designed reinforced con¬ 
crete building increases with age, the concrete 
constantly gaining in strength and the bond with 
the steel becoming stronger. 

DURABILITY. 

There is scarcely any class of manufacture 
which is not now being carried on in a rein¬ 
forced concrete building. It is adaptable to 
any weight of loading, to high speed and heavy 
machinery, as well as to light machine tools, and 
to almost any style of design. 

Recent scientific experiments, as well as actual 
experience, are favorable to the use of concrete 
under repeated and vibrating loads. 

The use of concrete in brackets for supporting 
crane runs, as in the Bullock shop, pages 45 to 50, 
is an interesting example of severe application 
of loading. Several concrete buildings in San 
Francisco withstood the shock of the earthquake, 
while those around them of brick and stone and 
wood were destroyed. 

While most materials tend to rust or decay 
with time, concrete under proper conditions con¬ 
tinues to increase in strength for months or even 
for years. 

Concrete expands and contracts with changes 
of temperature. Its co-efficient of expansion, 
that is, its expansion in a unit length for each 
degree of increase in temperature, is almost 
identical with steel, and on this account there is 
no tendency of the steel to separate from the con¬ 
crete, and they act together under all conditions. 
As in building with other materials, provision 
must be made in long walls or other surfaces for 
the expansion and contraction due to tempera¬ 
ture, by placing occasional expansion joints or 
by adding extra steel. In factories of ordinary 
size, no special provision need be made, as the 
regular steel reinforcement will prevent cracking. 

Special precautions are necessary for laying 
concrete in sea water. A first class cement must 
be selected, rich proportions used—at least 1:2:4 
—a coarse sand, and well proportioned aggregate 
which will produce a dense impervious mass. 


FIRE RESISTANCE. 

Reinforced concrete ranks with the best fire¬ 
proof materials, and it is this quality perhaps 
more than any other which is responsible for 
the enormous increase in its use for factories. 

Intense heat injures the surface of the con¬ 
crete, but it is so good a non-conductor that it 
provides ample protection for the steel rein¬ 
forcement, and the interior of the mass is unaf¬ 
fected even in unusually severe fires. 

For efficient fire protection in slabs, under 
ordinary conditions the lower surface of the steel 
rods should be at least % inch above the bottom 
of the slab. In beams, girders and columns, a 
thickness of iy 2 to 2% inches of concrete out¬ 
side of the steel, varying with the size and im¬ 
portance of the member, and the liability to 
severe treatment, is in general sufficient. In 
columns whose size is governed by the loads to 
be sustained, an excess of sectional area should 
be provided so that if, say, 1 inch of the surface 
is injured by fire, there will still be enough con¬ 
crete to sustain any loads which may subse¬ 
quently come upon it. 

One of the advantages of concrete construc¬ 
tion as a fireproof material is that the design 
may be adapted to the local conditions. For 
example, in an isolated machine shop where 
scarcely any inflammable materials are stored, 
it is a waste of money to provide a thick mass 
of concrete simply to resist fire. On the other 
hand, for a factory or warehouse storing a prod¬ 
uct capable of producing not merely a hot fire— 
a hot short fire will not damage seriously—but an 
intense heat of long duration, special provision 
may be made by using an excess area of concrete 
perhaps two or three inches thick. 

Actual fires are the best test of a material. 
One of the most severe on record occurred in the 
Pacific Coast Borax Refinery described on pages 
76 to 82, and the concrete there, as well as in the 
Baltimore and San Francisco fires, made an 
excellent record. 

The best fire resistant materials for con¬ 
crete are first-class Portland cement with quartz 
sand and broken trap rock. Limestone aggre¬ 
gate will not stand the heat so well as trap, while 
the particles of gravel are more easily loosened 
by extreme heat. Neither of these materials, 
however, if of good quality, need be rejected for 
building construction unless the demands are 
especially exacting and the liability to fire great. 
Cinders make a good aggregate for fire resist- 


8 


ance, but the concrete made with them is not 
strong enough for reinforced concrete construc¬ 
tion except in slabs of short span or in partition 
walls. 

The fire resistance of concrete increases with 
age, as the water held in the pores is taken up 
chemically and is evaporated. 

INSURANCE. 

When reinforced concrete first came to the 
front for factories and warehouses, the insur¬ 
ance companies hesitated to assume suph build¬ 
ings as first-class risks. However, examination 
and tests have gradually convinced the most 
skeptical of their true fire resistance, until new 
structures of this material are sought after and 
given the lowest rates of insurance. 

Mr. L. H. Kunhardt, Vice-President and Engi¬ 
neer of one of the oldest of the Factory Mutual 
Insurance Companies, which have for years 
played a leading part in the development of mill 
construction, and the science of fire protection 
engineering and consequent reduction of fire 
losses, presents in an appendix to this chapter 
(p.ll) very instructive figures comparing the 
costs of insurance upon several types of factories 
for various classes of manufacture. Mr. Kun¬ 
hardt also indicates the means by which concrete 
may be utilized in reducing even the present low 
rates of insurance upon buildings protected by 
efficient fire apparatus. 

From the statements there given by so eminent 
an authority on mill insurance, we may conclude 
that a well-designed reinforced factory with con¬ 
tinuous floors (1) offers security against dis¬ 
astrous fires and total loss of structure; (2) re¬ 
duces danger to contents by preventing the 
spread of a fire; (3) prevents damage by water 
from story to story; (4) makes sprinklers un¬ 
necessary in buildings whose contents are not 
inflammable; (5) reduces danger of panic and 
loss of life among employees in case of fire. 

STIFFNESS. 

A reinforced concrete building really resembles 
a structure carved out of a single block or solid 
rock. It is monolithic throughout. The beams 
and girders are continuous from side to side and 
from end to end of the building, while even the 
floor slab itself forms a part of the beams, and 
the columns are also either coincident with them 
or else tied to them by their vertical steel rods. 

All this accounts for the extraordinary stiff¬ 
ness and solidity of a reinforced concrete struc¬ 


ture, and differentiates it from timber construc¬ 
tion, where positive joints occur over every col¬ 
umn ; and even from steel construction, in which 
the deflection is greater. 

FREEDOM FROM VIBRATION. 

This solidity and entire lack of joints, and par¬ 
ticularly the weight of the material, especially 
adapts it to both high speed and heavy machin¬ 
ery. The vibrations are deadened and absorbed 
in a way which is impossible in steel structures. 

An interesting example of this fact is fur¬ 
nished in the Ketterlinus building described on 
pages 30 to 34, where the vibration and jar in the 
new concrete building are remarkably less than 
in the adjacent steel and tile structure carrying 
the same type of machinery. 

VERSATILITY OF DESIGN. 

Steel rods are set in the concrete, to provide 
tensile strength, in such quantity and location as 
is needed for special loading for which it is de¬ 
signed. Consequently, spans can be constructed 
of any reasonable length, either long or short, 
and column spacing may be adapted to the re¬ 
quirements of operation. Because of the weight 
of the concrete, which must itself be borne by the 
strength of the member, very long beam and 
girder spans are relatively more expensive than 
the more ordinary spans of 15 or 20 feet. Simi¬ 
larly, the cost of floor slabs per square foot in¬ 
creases appreciably with their span. These limi¬ 
tations are economical rather than theoretical, 
and every design should therefore be studied 
thoroughly to produce the best results at least 
cost, and to adapt the structure to the class of 
manufacture or storage for which it is intended. 

The rule applies to reinforced concrete as well 
as to other structures, that the industrial por¬ 
tion of the plant, the arrangement of the ma¬ 
chines, and of the transmission machinery, 
should be first designed and the structure 
adapted to give a minimum operating expense. 

LIGHT. 

A special feature of reinforced concrete con¬ 
struction is the possibility of building practically 
the entire wall of glass, so as to afford a maxi¬ 
mum amount of light. Concrete is so strong that 
the columns can be made of small size and the 
windows carried by shallow beams. The win¬ 
dow area may thus cover a very large percentage 
of the wall surface. 

WATERTIGHTNESS. 

In some classes of manufacture where water 


9 


is freely used, as in paper and pulp mills, it is 
essential that the floors shall be tight so that 
water cannot fall upon the product on the floor 
below or onto the belting. In case of fire a 
watertight floor prevents damage from water to 
the machinery and materials in the stories below. 

A concrete floor with granolithic surface is prac¬ 
tically impervious to water. 

CLEANLINESS. 

Concrete floors may be laid on a slight slope 
with a drain along the sides of the room so as to 
carry off all water and permit flushing with the 
hose. Concrete is vermin proof. 

RAPIDITY OF CONSTRUCTION. 

The speed with which a reinforced concrete 
building can be completed is due in a great meas¬ 
ure to the fact that there need be no waiting 
for materials. Sand and stone are always avail¬ 
able; Portland cement is now supplied by large 
mills with immense storage capacity; and steel 
rods are kept in stock, so that a building can be 
commenced as soon as the plans are completed 
and no delays need be incurred in ordering spe¬ 
cial shapes and awaiting their shipment from the 
mills. 

In general under good superintendence the rate 
of progress of a reinforced concrete factory may 
be as fast as one-half story or even one story per 
week. 

HANGING SHAFTING. 

Provision may be made for shafting by placing 
bolts or sockets in the beams to connect with 
pillow blocks for special lines of shafting, or such 
connections may be made at regular intervals so 
that timbers or steel frames may be bolted and 
shafting, or tracks for conveying material, sup¬ 
ported at any positions subsequently specified. 

ROOF. 

Naturally, the roof of a reinforced concrete 
building is of the same material, designed to 
carry the weight of roof covering and snow 
which may come upon it. It is advisable to cover 
with some one of the standard form of roofings. 

If the building is erected with a view to adding 
one or more stories, it is well to build the roof 
of wood or light steel construction so that it may 
be readily taken down or raised. Often the roof 
slab is made of concrete sufficiently strong to 
afterward become a floor slab. When this is 
done, drainage is obtained by placing on the slab 


a temporary fill of cinder concrete, properly 
sloped. 

-TANKS. 

The making of durable tanks is one of the 
problems in many factories. This is being solved 
in numerous cases by the use of reinforced con¬ 
crete, designed with sufficient steel to resist the 
water pressure. In paper and pulp mills the 
adoption of concrete tanks is especially advisable 
because of the frequent repairs and renewals re¬ 
quired in wood construction. Special attention 
should be given to the watertightness of con¬ 
crete by grading all the aggregates and by care in 
placing. 

LETTING THE CONTRACT 

The contract for the construction of a rein¬ 
forced concrete factory should be let only to re¬ 
sponsible builders with practical experience in 
this class of work. A man who has simply laid 
concrete foundations is not competent to erect 
a factory building. 

If day labor is employed, it must be under the 
direct superintendence of an engineer skilled in 
concrete construction. 

The plan is frequently followed of requesting 
estimates from different contractors without 
specifying the requirements of the design. As a 
consequence, the man who dares to figure with 
the smallest factor of safety, and who thus would 
build the poorest and weakest structure, presents 
the lowest bid. Such a possibility may be pre¬ 
cluded by having at least the general plans and 
specifications prepared in advance by a compe¬ 
tent engineer or architect, so that the estimates 
may be compared with fairness. 

Concrete building construction is frequently 
performed on the cost-plus-a-fixed-sum or cost- 
plus-a-percentage basis. These methods are apt 
to result in a somewhat higher cost for the 
structure than competitive bidding, although 
they offer less temptation to the builder. 

Whatever plan is followed, one or more com¬ 
petent inspectors should be employed by the 
owners independent of the contractor to see that 
the work is properly performed in all its details. 

GROWTH OF REINFORCED CONCRETE. 

One of the first uses of reinforced concrete in 
building construction was in the house erected 
by W. E. Ward in 1872 at Port Chester, N. Y. 
Some twenty years earlier than this, in France, 
the first combinations of iron imbedded in con- 


10 


Crete were made in a small way. However, not 
until the very end of the last century, since 1895, 
has concrete been employed commercially in the 
construction of buildings. Previous to this it had 
attained a wide use in foundations, and at this 
time its development was beginning for such 
structures as dams, sewers and subways. 

Two principal reasons may be offered for this 
comparatively slow growth followed by such 
marvelous activity. In the first place, Portland 
cement manufacturers, beginning in Europe 
about the middle of the 19th century and in 
the United States about 1880, finally produced a 
grade of cement which, with the inspection nec¬ 
essary for all structural materials, could be de¬ 


pended upon to give uniform and thoroughly re¬ 
liable results; furthermore, along with the per¬ 
fection of the process of manufacture, the price 
gradually fell from the high cost per barrel in 
1880 for imported cement, to a figure for domes¬ 
tic Portland cement of equally good, if not better, 
quality, at which concrete in plain form could 
compete with rough stone masonry, and with 
steel imbedded could compete with other build¬ 
ing materials. 

In the second place, theoretical studies and 
practical experiments have now produced rational 
and positive methods for computing the strength 
of concrete reinforced with steel so that absolute 
dependence can be placed upon it. 


FIRE INSURANCE ON FACTORIES OF REINFORCED CONCRETE. 

By L. H. Kunhardt, Vice-President, Boston Manufacturers’ Mutual Fire Insurance Co. 


In consideration of the question of insurance 
on reinforced concrete factories, the problem 
simply resolves itself into a determination of 
what the fire and water damage will be in the 
event of fire compared with that in other types 
of factory buildings. For this purpose concrete 
factories may be divided into two classes: 

1st. Those having contents which are not in¬ 
flammable or readily combustible. In this class, 
if wooden window frames and partitions, etc., 
have been eliminated, the building as a whole 
becomes practically proof against fire, provided 
there are no outside exposures, protection against 
which would require special precautions. 

2nd. Those having contents which are more 
or less combustible, and which have in their con¬ 
struction small amounts of inflammable mate¬ 
rial such as wooden window frames and top floors. 


In this class the burning of contents is the cause 
of damage to the building, the extent of which 
is determined by the character of the contents. 

Of the two, the latter class is the one ordi¬ 
narily met, and with which the question of in¬ 
surance cost is therefore usually concerned. The 
character of the occupancy, details of construc¬ 
tion and conditions of various kinds inside and 
outside the factory, and in the various communi¬ 
ties, have such direct bearing on rates that any 
statement as below of comparative cost must be 
extremely approximate, but perhaps of value as 
showing somewhat the relative costs. These in 
the following table are made upon the basis of a 
building without a standard fire equipment, 
which condition is, however, now rare in the case 
of first-class factories and warehouses, even if of 
fireproof construction. 


CONCRETE FACTORIES VS. THOSE OF WOOD OR BRICK. 

Approximate Yearly Cost of Insurance per $100. Exposures, None; Area Not Large; Good City 
Department; No Private Fire Apparatus Except Such as Pails and Standpipes. 



All Concrete 

Brick Mill Construc¬ 
tion or Open Joists 

Wood Mill Construc¬ 
tion or Open Joists 

Add for Brick or Wood Build¬ 
ings in Small Towns and Cities 
Without Best of Water and 


Bldg. 

Contents 

Bldg. 

Contents 

Bldg. 

Contents 

Fire Departments 

General Storehouse. 

20c. 

45c. 

60c. 

100c. 

100c. 

125c. 

25c. 

Wool Storehouse. 

20c. 

35c. 

40c. 

60c. 

75c. 

125c. 

25c. 

Office Building. 

15c. 

35c. 

45c. 

75c. 

100c. 

150c. 

25c. 

Cotton Factorv. 

40c. 

100c. 

150c. 

250c. 

200c. 

300c. 

50c. 

Tannery. 

20c. 

40c. 

100c. 

125c. 

100c. 

100c. 

25c. 

Shoe Factory. 

25c. 

80c. 

100c. 

125c. 

150c. 

200c. 

50c. 

Woolen Mill. 

30c. 

80c. 

100c. 

125c . 

150c.. 

200c. 

50c. 

Machine Shop. 

15c. 

30c. 

65c. 

75c. 

100c. 

125c. 

25c. 

General Mercantile Building. . 

35c. 

75c. 

65c. 

. 125c. 

100c. 

150c. 

25c. 


Note. —Table corrected to April 1, 1918. 

Note. —These costs are based on the absence of automatic sprinklers and other private fire protective appliances of the 
usual completely equipped building. They are not schedule rates, but may be an approximation to actual costs under favorable 
conditions based on examples in various parts of the country. 

Note. —The rates on Mill Construction are generally lower than those on joist construction, but the figures in columns 3, 4, 
5 and 6 are a fair average between the two. 
















The foregoing table illustrates the gain 
by the use of the better type of construction, but 
in factory work it has long been recognized that 
there is a distinct hazard in the manufacturing 
operations and inflammable contents which is 
greater in degree than in other classes of prop¬ 
erty. The science of fire protection with auto¬ 
matic sprinklers and auxiliary apparatus has 
therefore attained such a degree of perfection 
that the brick or stone factory with heavy plank 
and timber floors is obtaining insurance at rates 
which are lower than those which are possible 
on any of the fireproof buildings without sprin¬ 
klers. The real reason for this lies in the fact 
that the contents, including machinery, stock in 
process, and finished goods, constitute by far the 
larger part of the value of the plant, and these 
the building alone cannot be expected to protect 
when a fire occurs within, except in so far as the 
absence of combustible material in construction 
may assist in so doing. Fire protection is there¬ 
fore needed for safety of contents, even if the 
building itself is practically fireproof. 

As illustrating the value of fire protection, I 
would state that in the Boston Manufacturers’ 
Mutual Fire Insurance Company, and others of 
the older of the Factory Mutual Companies, the 
average cost of insurance on the better class of 
protected factories has now for some years aver¬ 
aged, excluding interest, less than seven (7) 
cents on each one hundred dollars of risk taken, 
and on first-class warehouses connected with 
them, one-half this amount. These figures can 
be compared with the table as illustrating the 
gain by the installation of proper safeguards for 
preventing and extinguishing fire. 

In these same protected factories and ware¬ 
houses the actual fire and water loss is less than 
four (4) cents on each one hundred dollars of 
insurance, and, being so small, it would seem that 
they must be almost impossible of reduction, but 
nevertheless it is possible. 

How can this be accomplished? This is the 
problem of the designer and builder of the con¬ 
crete factory. 


1st. By avoiding vertical openings through 
floors—a common fault in many factories with 
wooden floors. To be a perfect fire cut-off, a floor 
should be solid from wall to wall, with stairways, 
elevators and belts enclosed in vertical concrete 
or solid brick walls having fire doors. 

2nd. By provision for making floors practi¬ 
cally waterproof, that water may not cause dam¬ 
age on floors below that on which fire occurs. 
Scuppers of ample size to carry water from floors 
to outside are an essential part of the design. In 
the ordinary factory with wooden floors, loss 
from water is almost invariably excessive as 
compared with the loss by actual fire. 

3rd. By making the buildings as incombust¬ 
ible as possible, thus reducing the amount of 
material upon which a fire may feed. Also by 
provision for sufficient thickness of fireproofing 
to thoroughly insulate all steel work, the fire¬ 
proofing being sufficiently substantial that it may 
not scale off ceilings or columns at a fire or from 
other causes, thus allowing failure of steel work, 
by heating or deterioration. An owner is thus 
more secure if the fire protection or any parts of 
it fail at a critical moment. 

4th. By judiciously limiting the area and 
values between vertical firewalls and by provid¬ 
ing subdivision walls of substantial design which 
will withstand the attack of the severest fires. 

5th. By good judgment as to the extent or 
amount of fire protection required in each indi¬ 
vidual case. While the value of the automatic 
sprinkler is recognized and the general rules 
specify its installation, the Factory Mutual Com¬ 
panies do not require it in the concrete building, 
except where there is sufficient inflammable ma¬ 
terial in the contents to furnish fuel for a fire. 
An essential feature of good factory construction 
includes not only consideration of the building, 
but protection adequate to its needs only. 

The extent to which the above is faithfully 
carried out will eventually be the determining 
feature in the cost of insurance. 

April 1, 1918. 


CHAPTER II—DESIGN 

Concrete is an artificial stone, and if it contains 
no steel, that is, if it is not reinforced, it is brittle 
like stone. Just as stone can be used to support 
enormous loads, as in foundations, bridges and 
dams, provided it is so placed as to receive no 
tension or pull, so can concrete stand heavy load¬ 
ing in compression with no reinforcement. 

Concrete, however, has the advantage of stone, 
because when built in place, steel, which is espe¬ 
cially adapted for withstanding pull, may be in¬ 
troduced at just the right position in the beam 
or other member to take this pull. In an ordi¬ 
nary beam the upper surface is in compression 
and the lower surface in tension; the natural 
arrangement of materials is therefore to design 
the beam so that the upper part is composed of 
concrete, which takes the compression, while 
steel is embedded near the bottom to resist the 
pull or tension. The concrete by surrounding the 
steel protects it from rust and fire, and because 
concrete and steel expand and contract almost 
exactly alike when heated and cooled, they may 
be used thus in combination with no danger of 
separation from changes in temperature. 

It is evident that to make a safe combination 
of concrete and steel it is necessary to know just 
how much load each can stand, and just where 
the steel must be located to take every bit of the 
tension which may occur in any part of the beam. 
While in a beam supported at the ends the pull 
is in the bottom and the principal steel must be 
as near to the bottom as is consistent with rust 
and fire protection, on the other hand, when the 
beam is built into a column or into another beam 
a load upon it produces also a pull at the top of 
the beam over its supports which tends to crack 
it there. Furthermore, there are other sec¬ 
ondary stresses in the interior of the beam, part¬ 
ly shear or tendency to slide and partly tension 
or pull, which must be guarded against by locat¬ 
ing steel rods in the proper places. Hence the 
necessity, because of the complication in the ac¬ 
tion of the stresses even in a single beam, that 
the designers have a knowledge of the principles 
of mechanics and the theories involved. 

It is not the purpose of this book to dwell upon 


AND CONSTRUCTION 

the theory of design, but instead to give practi¬ 
cal principles of construction to supplement the 
theory which can be obtained readily from other 
sources. 

CEMENT. 

For all important concrete construction it is 
the practice to require that the Portland cement 
shall pass the Standard Specifications for Port¬ 
land cement of the American Society for Testing 
Materials. 

SAND. 

Since it is impossible for even the most expert 
engineer to determine positively by inspection 
whether or not a sand is fit to be used in con¬ 
crete, it is absolutely necessary that it should be 
tested for important work. 

The difficulties are that the impurities, while 
affecting the chemical combination with the ce¬ 
ment, may be so minute as to be impossible to 
distinguish by the eye. 

An extremely small percentage of vegetable 
matter of certain kinds may delay the hardening 
of the cement so that at seven days there is prac¬ 
tically no strength in the concrete or mortar. 

SPECIFICATIONS FOR AGGREGATES. 

The following specifications are of so general 
a character as to be applicable to nearly all kinds 
of concrete construction. 

Fine Aggregates.*—The fine aggregate shall 
consist of sand, crushed stone or gravel screen¬ 
ings passing when dry a screen having 14 -inch 
diameter holes, or a screen having 4 meshes to 
the linear inch. It shall be clean, coarse and 
free from vegetable loam and other deleterious 
matter. Not more than 30 per cent by weight 
shall pass a sieve having 50 meshes per lineal 
inch. Mortars composed of 1 part Portland 
cement and 3 parts fine aggregate, by weight, 
when made into briquettes, shall show a tensile 
strength of at least 90 per cent of the strength 
of 1:3 mortar of the same consistency made with 
the same cement and standard Ottawa sand. To 
avoid the removal of any coating on the grains 
which may affect the strength, bank sands shall 
not be dried before being made into mortar, but 
shall contain natural moisture. The percentage 


13 


of moisture may be determined upon a separate 
sample for correcting weight. From 10 to 40 
per cent more water may be required in mixing 
bank or artificial sands than for standard Ottawa 
sand to produce the same consistency. 

Coarse Aggregates.*—The coarse aggregate 
shall consist of inert material, such as crushed 
stone or gravel, which is retained on a screen 
having ^-inch diameter holes. The particles 
shall be clean, hard, durable, and be free from all 
deleterious matter. Aggregates containing soft, 
flat or elongated particles should be excluded 
from reinforced concrete. A gradation of sizes 
of the particles is advantageous. The maximum 
size of the coarse aggregate shall be such that it 
will not separate from the mortar in laying and 
will not prevent the concrete fully surrounding 
the reinforcement or filling all parts of the forms. 
Where concrete is used in mass the size of the 
coarse aggregate may be such as to pass a 3-inch 
ring. For reinforced concrete a size to pass a 
1-inch ring or a smaller size may be used. 

Gravel.*—The gravel shall be composed of 
clean pebbles free from sticks and other foreign 
matter and containing no clay or other material 
adhering to the pebbles in such quantity that it 
cannot be lightly brushed off with the hand or 
removed by dipping in water. It shall be 
screened to remove the sand which shall after¬ 
ward be remixed with it in the required propor¬ 
tions. 

Broken Stone.*$—The broken or crushed stone 
shall consist of pieces of hard and durable rock, 
such as trap, limestone, granite, or conglomerate. 
The dust shall be removed by a sand screen, to 
be afterward, if desired, mixed with and used as 
a part of the sand, except that if the product of 
the crusher is delivered to the mixer so regularly 
that the amount of dust, as determined by fre¬ 
quently screening samples, is uniform, the 
screening may be omitted, and the average per¬ 
centage of dust allowed for in measuring the 
sand. 

Water.*—The water shall be free from oil, 
acid, strong alkalies, or vegetable matter. 

REINFORCING STEEL 

The steel reinforcement shall be free from ex¬ 
cessive rust, scales, or coatings of any character, 

♦Paragraphs designated by an asterisk are quoted with per¬ 
mission from Taylor & Thompson’s “Concrete, Plain and 
Reinforced.” Second Edition. 

tThe maximum size of stone for building construction is cus¬ 
tomarily limited to 1 inch or 114 inches, so that the concrete 
may be carefully placed around the steel and into the corners 
of the forms. In certain cases %-inch or %-inch stone is 
specified, hut the larger size is better, provided it can he 
properly placed. 


which tend to reduce or destroy the bond with 
the concrete. The steel shall conform to the re¬ 
quirements of the American Society for Testing 
Materials. . 

For temperature reinforcement steel of high 
elastic limit and deformed section is especially 
good. 

PROPORTION OF MATERIALS. 

In building construction, the proportions most 
generally adopted are 1 part cement to 2 
parts sand to 4 parts broken stone or gravel (this 
being customarily indicated by the expression 
1:2:4). One bag (4 bags to barrel) of Portland 
cement is considered as 1 cubic foot, thus propor¬ 
tions 1:2:4 mean one bag Portland cement, 2.0 
cubic feet sand measured loose and 4.0 cubic feet 
of broken stone or gravel measured loose. Such 
concrete when made into cylinders 6 inches in 
diameter by 12 inches long must test 2,000 
pounds per square inch at the age of 28 days. 

On a small job, where tests cannot be made so 
economically, it is well to be conservative and 
require proportions 1:2:4. On the other hand, if 
an engineer is constantly present, it is often best 
not to definitely specify the relative amount of 
sand to stone, but to permit the proportion to 
vary with the material; thus, in laying the con¬ 
crete if there is an excess of mortar the quantity 
of sand should be slightly reduced and the quan¬ 
tity of stone correspondingly increased, while if 
there is insufficient mortar to cover the stone and 
prevent stone pockets, the sand may be increased 
and the stone decreased. The proportion of ce¬ 
ment to the sum of the parts of sand and stone 
may thus be kept constant. 

CONSISTENCY. 

For building construction and for other rein¬ 
forced concrete work while it is necessary that 
the concrete shall be mixed wet enough to flow 
sluggishly around and thoroughly imbed the steel 
it must be no wetter than is required to attain 
this result. If mixed too dry, air voids will be 
left around the stone, and stone pockets will 
appear on the face of the concrete after removing 
the forms. If, on the other hand, too much 
water is added, the surface may have a similar 
appearance because of the water running away 
from the stone. Furthermore, and of greater 
importance than the mere appearance, an excess 
of water reduces the strength of the concrete 
maybe to two-thirds or less of its normal 
strength. 


14 



PLACING. 

Concrete shall be conveyed to place in such 
a manner that there shall be no distinct separa¬ 
tion of the different ingredients, or in cases 
where such separation inadvertently occurs the 
concrete shall be remixed before placing. Each 
layer in which the concrete is placed shall be of 
such thickness that it can be incorporated with 
the one previously laid. Concrete shall be used 
so soon after mixing that it can be rammed or 
puddled in place as a plastic homogeneous mass. 
Any, which has set before placing, shall be re¬ 
jected. When placing fresh concrete upon an 
old concrete surface, the latter shall be cleaned 
of all dirt and scum or laitance and thoroughly 
wet. Noticeable voids or stone pockets discov¬ 
ered when the forms are removed shall be imme¬ 
diately filled with mortar mixed in the same 
proportions as the mortar in the concrete. For 
horizontal joints in thin walls, or in walls to 
sustain water pressure, or in other important 
locations, a joint of neat cement paste shall be 
used. 

If the concrete is conveyed by inclined chute 
or spout the angle of slope shall be 2 horizontal 
to 1 vertical. 

SURFACES. 

The proper treatment to give a pleasing ap¬ 
pearance to exposed surfaces is one of the most 
difficult problems in concrete building construc¬ 
tion. The surfaces of columns, beams and the 
under sides of floors can be made sufficiently 
smooth by careful spading, and by seeing to it 
that the mortar comes to the face and that the 
forms are tight enough to prevent the mortar 
running out. 

The treatment of the outside surface is deter¬ 
mined by the character of the structure. A fair 
surface, suitable for work which is not exposed 
to view, and even for sheds or other buildings 
where the appearance need not be regarded, may 
be obtained by using a very wet mixture of con¬ 
crete and by careful spading, as described above. 

When the character of building and its loca¬ 
tion is such as to warrant the obtaining of an 
excellent finish, this may be done by either dress¬ 
ing the surface after the forms are removed with 
a pointed hammer, by washing, or by rubbing 
with a block of carborundum or similar sub¬ 
stance. These three methods, together with 
others, are described in detail and illustrated in 
the chapter on Details of Construction, and the 
methods adopted in different buildings are taken 
up in the descriptive chapters which follow. 


FORMS. 

fThe lumber for the forms and the design of 
the forms shall be adapted to the structure and 
to the kind of surface required on the concrete. 
For exposed faces the surface next to the con¬ 
crete shall be dressed. Forms shall be suffi¬ 
ciently tight to prevent loss of cement or mortar. 
They shall be thoroughly braced or tied together 
so that the pressure of the concrete or the move¬ 
ment of men, machinery or materials shall not 
throw them out of place. Forms shall be left in 
place until, in the judgment of the engineer, the 
concrete has attained sufficient strength to resist 
accidental thrusts and permanent strains which 
may come upon it. Forms shall be thoroughly 
cleaned before being used again. 

The time for removal of forms is determined 
by the weather conditions and actual inspection 
of the concrete. The following approximate 
rules may be followed as a safe guide to the mini¬ 
mum time for the removal of forms.f 

Walls in Mass Work.—One to three days, or 
until the concrete will bear pressure of the thumb 
without indentation. 

Thin Walls.—In summer, two days; in cold 
weather, five days. 

Slabs Up to Six Feet Span.—In summer, six 
days; in cold weather, two weeks. 

Beams and Girders and Long Span Slabs. In 
summer, ten days or two weeks; in cold weather, 
three weeks to one month. If shores are left 
without disturbing them, the time of removal of 
the sheeting in summer may be reduced to one 
week. 

Column Forms.—In summer, two days; in cold 
weather, four days, provided girders are shored 
to prevent appreciable weight reaching columns. 

A very important exception to these rules ap¬ 
plies to concrete which has been frozen after 
placing, or has been maintained at a temperature 
just above freezing. In such cases the forms 
must be left in place until after warm weather 
comes, and then until the concrete has thor¬ 
oughly dried out and hardened. 

FOUNDATIONS. 

In a reinforced concrete building, the floor 
loads are carried by the slabs to the beams and 
girders, and thence to the columns, which con¬ 
centrate the weight upon small areas of ground. 
The footing of each column must therefore be 
spread over a large enough area of ground so as 
not to overcompress the soil and cause appreci¬ 
able settlement. 

fFrom paper on “Forms for Concrete Construction,” by 
Sanford E. Thompson, before National Association of Cement 
Users, 1907. 


15 


*Mr. George B. Francis suggests the following 
loading for materials which can be clearly de¬ 
fined, at the same time calling attention to the 
necessity for varied and ample experience when 
fixing allowable pressures in any particular case: 

Ledge rock, 36 tons per square foot. 

Hard pan, 8 tons per square foot. 

Gravel, 5 tons per square foot. 

Clean sand, 4 tons per square foot. 

Dry clay, 2 tons per square foot. 

Wet clay, 2 tons per square foot. 

Loam, 1 ton per square foot. 

To illustrate the use of these rules: If a col¬ 
umn 20 inches square carries a load from above 
of 80 tons, the footing over a soil of dry sand 
must cover an area of 8 % = 20 square feet; that 
is, the footing must be about 4 feet 6 inches 
square. 

Not only must the area be calculated to dis¬ 
tribute the load over a proper area of soil, but 
the thickness of the footing must be computed 
so as to prevent the column punching or shearing 
through it, and a sufficient amount of reinforc¬ 
ing steel must be placed in the bottom of the 
concrete footing to prevent its buckling and 
breaking from the concentrated load of the col¬ 
umn. The size of the rods is calculated from the 
bending moment produced by the upward pres¬ 
sure of the soil against the projection of the foot¬ 
ing, which may be assumed to be a beam sup¬ 
ported upon a line running through the center of 
the column. If, as is customary, the footing pro¬ 
jects in both directions and the rods run in both 
directions, both projections may be taken into 
account as resisting the pressure. 

In certain cases, where a very large footing is 
required, especially when the footing rests on 
piles, stirrups may be needed to resist shear or 
diagonal tension, as in an ordinary beam. 

Proportions of concrete for reinforced foot¬ 
ings may be 1:21/^ :5, i.e., one part Portland ce¬ 
ment to 21/2 parts sand to 5 parts broken stone or 
gravel, or the same proportions may be used as 
in the building above them. 

Foundations in dry ground which do not re¬ 
quire reinforcement and sustain only direct com¬ 
pression may be laid in proportions of 1:3:6 or 
1:3:7. If laid under water the concrete should 
not be leaner than 1 :2i/ 2 :5, while for sea water 


•Taylor & Thompson’s “Concrete, Plain and Reinforced,” 
Second Edition, page 639. 


construction a mixture at least as rich as 1:2:4 
is advisable, with very careful testing of the 
cement and aggregates. 

For a building with no basement, foundation 
walls between the columns are unnecessary. The 
walls may be started just below the surface of 
the ground, and each wall slab will form of itself 
a beam supported at each end by the column 
foundation. When a basement is included in the 
design, its wall is apt to act as a retaining wall 
to resist the pressure of earth, and it may be 
necessary to calculate the thickness and rein¬ 
forcement required to resist the earth pressure. 
Frequently, the bottom of the wall is held by the 
basement floor, and the top by the first floor of 
the building. In this case it may be considered 
as a slab supported at the bottom and top, and 
the principal reinforcing rods should be vertical 
and placed about one inch from the interior face 
of the wall. If there is no support at the top, the 
footing may be enlarged by careful computation 
and a cantilever design made with the principal 
tension rods vertical, but near the exterior face 
of the wall; or the vertical slab may be sup¬ 
ported at the ends by columns or buttresses of 
proper design, and the tension rods, computed to 
resist the earth pressure, run horizontally near 
the interior face. 

For an ordinary cellar wall supported at bot¬ 
tom and top, a thickness of 8 inches, with %-inch 
vertical rods about one foot apart will be strong 
enough to hold the earth, but it is best to actually 
compute the thickness and reinforcement for 
any given case. Even if the principal rods are 
vertical, occasional horizontal rods, spaced about 
18 inches or 2 feet apart, should be placed in the 
wall to tie it together and prevent contraction 
cracks. 

BASEMENT FLOOR. 

The earth under a basement floor must be well 
drained. If necessary, drains of tile pipe or of 
screened gravel or stone may be placed in 
trenches just below the concrete, or the entire 
level may be covered with cinders or stone. If the 
basement is below tide water or ground water 
level, it is not safe to depend upon the concrete 
itself being water-tight, and a layer of water¬ 
proofing consisting of four to six layers of tarred 
paper, mopped on, may be spread on the con¬ 
crete and carried up in continuous sheets on the 
walls to above water level, and the whole surface 
covered with another layer of concrete. In some 
cases it may be necessary to make the concrete 


16 



extra thick, or to add reinforcement, to resist 
the upward pressure of the water. 

For a basement floor in dry ground a 3-inch or 
4-inch thickness of ordinary 1:3:5 concrete— 
that is, concrete composed of 1 part Portland 
cement to 3 parts sand to 5 parts broken stone 
or gravel—may be laid and the surface screeded 
to bring it to the required level. As it sets, this 
concrete should be troweled just as the wearing 
surface of a sidewalk is troweled, but without the 
mortar or granolithic finish which is customarily 
laid upon a walk. If the floor is to have a great 
deal of wear or trucking, the usual %-inch or 
1-inch layer of 1:2 mortar may be laid upon the 
concrete before it has set, forming a part of the 
total thickness of 4 inches; but usually this is an 
unwarranted expense in a basement, as the plain 
concrete will give as good service. 

It is well in any case to divide the floor into 
blocks, say 8 or 10 feet square, so that any 
shrinkage cracks will come in the joints. This 
is readily accomplished by laying alternate 
blocks, and then filling in the intermediate ones 
the next day. 

DESIGN OF FLOOR SYSTEM. 

LOADING.—In designing a reinforced con¬ 
crete building, the first consideration is the load¬ 
ing which the various floors must sustain. In 
addition to the specified live or superimposed load 
the weight of the concrete itself must always be 
allowed for. 

The various conditions met with in warehouse 
or factory construction may necessitate loadings 
varying from 75 to 1,000 pounds per square foot 
of floor area. As a guide to the selection of floor 
loads, the following values are suggested: 

Office floors.75 pounds per square foot 

Light running machinery, 

75 to 150 pounds per square foot 
Medium heavy machinery. .200 pounds per square foot 

Heavy machinery .250 pounds per square foot 

Storage of parts or finished 

products, depending upon 

actual calcuated loads, 

150 to 1,000 pounds per square foot 

When the loads are apt to occur only over a 
part of the floors, the slabs and beams are calcu¬ 
lated for the full load, but a reduction of 15 per 
cent of the live load may be allowed in figuring 
the girders. 

In the case of floors supporting machinery 
whose weight is slight but whose motions are 
great, a proper allowance should be made to take 
care of the resulting vibrations. 

LAYOUT.—The arrangement of the floor 


beams, girders and columns depends upon so 
many considerations that special study is re¬ 
quired in each case. 

For heavy loads, say 250 pounds per square 
foot and over, bays 14 feet by 14 feet are gen¬ 
erally the cheapest, while for light loads prob¬ 
ably 18 feet by 18 feet is the most economical 
arrangement of bays. 

In order to secure the most economical arrange¬ 
ment of beams and girders it is frequently nec¬ 
essary to make several comparative estimates 
with different spacings of these members. 

The smallest amount of material is required 
with floor panels of short span and frequent floor 
beams to support them. However, the fact that 
the actual amount of material required for a cer¬ 
tain floor construction is less than that required 
in another does not always mean that this floor 
construction is actually the cheapest. If, for 
example, the beams are closer together it must 
be remembered that the unit labor for the form 
work is increased, and also that of the steel labor. 

The design of a complete floor system with re¬ 
inforced concrete beams, girders, slabs and col¬ 
umns, is shown by the isometric view in Fig. 3 
(p. 18). The columns are spaced 18 by 19 feet 
on centers and the floor is designed to support a 
live load of 250 pounds per square foot. 

FLOOR SLABS.—The thickness and rein¬ 
forcement of the floor slabs is determined 
by the distance between the beams, and by the 
loading which will come upon them. The most 
usual thicknesses are Sy 2 inches to 5 inches, with 
reinforcement calculated from the bending mo¬ 
ment produced by the loads. An economical 
quantity of steel is apt to be from 0.8 per cent 
to 1 per cent of the sectional area of the slab 
above the steel. 

A few rods are usually placed at right angles 
to the main bearing rods of the slab to assist in 
preventing contraction cracks, and these also add 
to the strength of the slab. 

In a factory or warehouse, the most economi¬ 
cal floor surface is generally a granolithic finish, 
consisting of a layer of 1:2 mortar about three- 
quarters inch thick, spread upon the surface of 
the concrete slab before it has begun to set, and 
troweled to a hard finish just like a concrete side¬ 
walk. 

Machines are readily bolted to the concrete by 
drilling small holes in the concrete at the proper 
points for the standards and grouting the lag 
screws in place, or else bolting them through the 
slab. 


17 





Fig. 3.—Isometric View of Design of Floor System. 


If for any reason a wood floor is required, 
stringers may be laid upon the top of the con¬ 
crete and spaces left between them or filled with 
cinders or with cinder concrete. 

BEAMS AND GIRDERS.—As already indi¬ 
cated, the sizes and reinforcement of the beams 
and girders must be accurately computed by one 
v/ho thoroughly understands the theories in¬ 
volved in reinforced concrete design. Even if 
tables are used the designer must have a knowl¬ 
edge of the mechanics and of the way in which 
the stresses act. 

It is a simple matter to determine the amount 
of steel required in the bottom of the beam to 
sustain the pull due to a given loading but while 
this is an important determination it is by no 
means the only one. 

The weak points in reinforced concrete struc¬ 
tures are not usually due to insufficient steel for 
tension, but more often to an ignorance of other 
smaller details not less important. It is thus 
absolutely dangerous, and, in fact, criminal, for 
a novice to design or pass upon drawings for a 
reinforced concrete structure. 

In beam and slab construction an effective 
bond must be provided at the junction of the 
beam and slab. When the principal slab rein¬ 


forcement is parallel to the beam or girder, trans¬ 
verse bars should be placed in the top of the slab 
extending over the beam and well into the slab 
on each side. 

Where the concrete in the web of beam and 
the slab is laid at one operation so that there can 
be no joint between them, the slab may be con¬ 
sidered as an integral part of the beam, and the 
beam figured as a T section. In this case the 
effective width of slab considered shall not ex¬ 
ceed one-fourth of the span length of the beam 
nor be greater than four times the thickness of 
the slab on either side of the edge of the web. 

The design of reinforced concrete beams and 
girders involves the following studies: 

(1) The bending moment due to the live and 
dead loads, this involving the selection of the 
proper formula for the computation. 

(2) Dimensions of beams which will prevent 
an excessive compression of the concrete in the 
top and which will give the depth and width 
which is otherwise most economical. 

(3) Number and size of rods to sustain ten¬ 
sion in the bottom of the beam. 

(4) Shear or diagonal tension in the concrete. 

(5) Value of'bent-up rods to resist shear or 
diagonal tension. 


18 





(6) Stirrups to supplement the bent-up rods 
m assisting to resist the shear or diagonal ten¬ 
sion. 

(7) Steel over the supports to take the ten¬ 
sion due to negative bending moment. 

(8) Concrete in compression at the bottom of 
the beam near the supports due to negative bend¬ 
ing moment. 

(9) Horizontal shear under flange of slab. 

(10) Shear on vertical planes between beams 
and flanges. 

(11) Distance apart of rods to resist splitting. 

(12) Length of rods to prevent slipping. 

(13) End connections at wall. 

Although it is not the province of this book 
to go into the mathematical treatment of these 
various points, many of them are as yet so in¬ 
adequately treated in literature on the subject 
that it will be advisable to touch upon them in a 
general way. 

fBENDING MOMENT.—In the design of rein¬ 
forced concrete beams and slabs as much varia¬ 
tion may be obtained in the results by the selec¬ 
tion of the bending moments as in the choosing 
of working stresses. When the beam or slab is 
designed as continuous over the supports it is 
absolutely necessary that the beam be really 
continuous both in design and in construction; 
that the stresses due to negative bending mo¬ 
ment at the support be provided for, and that the 
steel be accurately placed. Under these condi¬ 
tions the following formulas are recommended as 
good practice: 

Let M = bending moment in foot pounds. 

w=load uniformly distributed in pounds 
per foot of length (both live and dead load). 

1 = length of member between centers of 
support in feet. 

To transform the bending moment to inch- 
pounds, multiply by 12. 

For beams and slabs truly continuous and 
thoroughly reinforced over the supports, 

M = %2 wl 2 at center and at support. 

For beams and slabs partially continuous, as 
end spans, or for continuous members of 2 or 3 
spans. 

M = Ll 0 wl 2 at center and adjoining support. 

For beams and slabs simply supported at the 
ends and not continuous. 

M = i/ 8 wl 2 . 

The negative bending moments which exist at 

tThe values to be used in determining bending moments, 
allowable unit stresses, moduli of elasticity, etc., are usually 
definitely specified in the Building Codes and Regulations of 
the larger cities 


the support in continuous beams must be pro¬ 
vided for by steel rods carried over the top of 
the support for tension and by a sufficient area 
of concrete and steel at the bottom of the beam 
near the support to take the compression. If the 
compression in the concrete at the bottom of the 
beam is excessive the beams must either be made 
deeper next to the support by forming a flat 
haunch or extra horizontal steel must be inserted. 
The tensile and compressive reinforcement over 
supports must extend sufficiently beyond the 
support to develop the requisite bond strength. 

fREINFORCEMENT.—The tensile stress in 
mild steel must not exceed 16,000 pounds per 
square inch. For cold twisted steel, because of 
its higher elastic limit and its deformed surface 
which distributes any cracking, a higher stress 
of 18,000 pounds may be used. The compressive 
stress in reinforcing steel must not exceed 16,000 
pounds per square inch nor more than 15 times 
the working compressive stress in the concrete. 

tSPACING OF BARS.—The lateral spacing of 
parallel bars should not be less than two and one- 
half diameters, center to center, nor should the 
distance from the side of the beam to the center 
of the nearest bar be less than two diameters. 
The clear vertical spacing between two layers of 
bars should not be less than i/ 2 inch. 

fCONCRETE.—If the concrete is made of 
first-class materials mixed not leaner than 1 part 
cement to 2 parts sand to 4 parts stone, so as to 
have a compressive strength of at least 2,000 
pounds per square inch at the age of 28 days, a 
value as high as 650 pounds per square inch for 
the extreme fiber compression in beams and slabs 
may be used with safety, provided the computa¬ 
tion is based on what is termed the straight-line 
distribution of stress, and the ratio of the modu¬ 
lus of elasticity of steel to concrete is taken at 
15. 

fWORKING STRESSES IN BEAMS AND 
SLABS.—The following working stresses are for 
concrete composed of 1 part Portland cement, 

2 parts sand and 4 parts broken stone or gravel 
and capable of developing an average compres¬ 
sive strength of 2000 pounds per square inch at 
28 days: 

a. Modulus of elasticity. The modulus shall 
be assumed as 1/15 that of steel; that is, a ratio 
of 15 shall be used. 

b. Compression in extreme fiber. The extreme 
fiber stress in beams and slabs calculated for con¬ 
stant modulus of elasticity shall be 650 pounds 


19 



per square inch. Adjacent to the support of con¬ 
tinuous beams, stresses 15 per cent higher may¬ 
be used. 

c. Bearing. For compression on surface of 
concrete larger than loaded area 650 pounds per 
square inch. 

d. Bond. The bonding stress between con¬ 
crete and plain reinforcing bars shall be 80 
pounds per square inch, and between concrete 
and deformed bars from 100 to 150 pounds per 
square inch, depending upon the character of 
the bar. 

fSHEAR AND DIAGONAL TENSION.—The 
bending of a beam produces a tendency of the 
particles within the beam to pull apart. It is 
therefore necessary to study the vertical shear, 
the horizontal shear and the diagonal tension in 
a beam. When the maximum shearing stresses 
exceed the value allowed in tension for the con¬ 
crete alone, web reinforcement must be provided 
to assist in carrying the diagonal tension stresses. 
This web reinforcement may consist of bent 
bars, or inclined or vertical members attached to 
or looped about the horizontal reinforcement. 
Where inclined members are used the connection 
to the horizontal reinforcement must be such as 
to insure against slip. Experiments prove that 
the bending up of the reinforcing bars in differ¬ 
ent adjoining planes increases the strength of 
the beam in shear to a very considerable extent, 
and that if the total shearing stress for 1:2:4 
concrete does not exceed 120 pounds per square 
inch we are justified in assuming that the con¬ 
crete carries one-third of the shear and the rein¬ 
forcement the balance. The following allowable 
values for the maximum shearing stress should 
be used.* 

a. For beams with horizontal bars only and 
without web reinforcement, calculated by the 

y 

formula v = 40 pounds per square inch. 

b. For beams thoroughly reinforced with web 
reinforcement, the value of the shearing stress 
being calculated according to the formula, 120 
pounds per square inch, the web reinforcement 
shall be proportioned to resist two-thirds of the 
shearing stresses, as computed by the formula. 

c. For punching shear, 120 pounds per square 
inch. 


*Taylor & Thompson, “Concrete, Plain and Reinforced,” 
Third Edition,. Page 39. 

fThe values to be used in determining bending moments, 
allowable unit stresses, moduli of elasticity, etc., are usually 
definitely specified in the Building Codes and Regulations of 
the larger cities. 


COLUMNS. 

The most important of all the members of the 
building are the columns, for if a column fails 
the entire building is liable to go down. 

Columns of short length, essentially piers, the 
length of which is not more than six times the 
least lateral dimension, may be built of plain 
concrete with no reinforcement, provided the 
loading is central. Columns longer than this 
should be reinforced for safety in construction 
and also to guard against the possibility of ec¬ 
centric loading and the danger of sudden failure. 

The ratio of the unsupported length of a col¬ 
umn to its least width should be limited to 15. 

The effective area of a column to use in figur¬ 
ing the compression should be less than the total 
area to allow a certain surface covering for fire 
protection. Where the contents of a building are 
especially inflammable this protective covering 
should be taken to a depth of 11/2 inches on all 
surfaces, but if the contents are not of a par¬ 
ticularly inflammable nature a decrease in the 
total diameter or width of a column of 1 to 2 
inches is a fair allowance. 

Columns may be reinforced by means of longi¬ 
tudinal rods, by bands or hoops, by bands or 
hoops together with longitudinal bars, or by 
structural shapes sufficiently rigid to act as col¬ 
umns themselves. Bands or hoops increase 
greatly the “toughness” of a column and its ulti¬ 
mate strength, but have little effect upon its be¬ 
havior within the elastic limit. They do, how¬ 
ever, tend to make the concrete a safer and more 
reliable material and should permit of a some¬ 
what higher working stress. 

The following are working stresses in the con¬ 
crete for the several types of columns: 

PLAIN COLUMNS.—Plain columns or piers 
whose length does not exceed 6 diameters, 25 
per cent of the compressive strength of 28 days 
or 500 pounds per square inch on 2,000-pound 
concrete. 

REINFORCED COLUMNS 

a. Columns with longitudinal reinforcement 
only, the unit stress recommended for plain col¬ 
umns, plus the allowance for the value of the 
longitudinal steel. 

b. For columns reinforced with not less than 
1 per cent, and not more than 4 per cent, of 
longitudinal bars, and with bands, hoops, or 
spirals, as specified above, a stress of 700 pounds 
per square inch, provided the ratio of the un- 


20 



supported length of the column to the diameter 
of the hooped core is not more than 100 . 

c. For the core of the structural steel column, 
350 pounds per square inch. 

In all cases, longitudinal steel is assumed to 
carry its proportion of stress in accordance with 
the ratio of modulus of elasticity of steel to 
modulus of elasticity of the concrete. 

Bars composing longitudinal reinforcement 
shall be straight, and shall have sufficient lateral 
support to be securely held in place until the con¬ 
crete has set. 

Where bands or hoops are used the total 
amount of such reinforcement shall not be less 
than 1 per cent of the volume of the column en¬ 
closed. The clear spacing of such bands or 
hoops shall not be greater than one-fourth the 
diameter of the enclosed column. Adequate 
means must be provided to hold bands or hoops 
in place so as to form a column, the core of which 
shall be straight and well centered. 

Bending stresses due to eccentric loads must 
be provided for by increasing the section and 
adjusting the steel until the maximum stress 
does not exceed the values above specified. 

The compressive strength of concrete is ap¬ 
proximately proportional to the amount of ce¬ 
ment which it contains, so that increasing the 
proportion of cement is an effective method of 
strengthening the column to permit smaller sec¬ 
tion. By using proportions of 1:1:3 a safe work¬ 
ing stress of 700 pounds per square inch may be 
adopted. If this is done the same mixture should 
be carried up through the floor so that there will 
be no weak places. 

WALLS. 

The walls of reinforced concrete factories are 
sometimes built up with the columns, but it is 
generally considered more economical to erect 
the skeleton structure and fill in the wall panels 
later, when columns forms are removed. 

Slots in the columns are made by nailing a 
strip on the inside of the column forms. In this 
ways the panels are mortised into the columns. 

Ordinary concrete walls require light rein¬ 
forcement to prevent shrinkage and give them 
stiffness while setting. All that is required for, 


say, a 4-inch or 6 -inch wall are 14 -inch bars 
spaced from 12 to 24 inches apart, according to 
the size and importance of the wall. At window 
and door openings a larger amount of reinforce¬ 
ment is of course necessary, and in these cases 
the amount of . steel must be calculated just as 
though the lintels were reinforced concrete 
beams. 

ROOFS. 

Reinforced concrete roofs are designed like 
floors. A roof load commonly assumed in tem¬ 
perate climates, to provide for roof covering, 
snow and wind pressure, is 40 pounds per square 
foot, in addition to the weight of the concrete 
itself. 

It is not safe to assume that the concrete roof 
of itself will be water-tight unless special provi¬ 
sion is made in the construction. Although tanks 
and walls can readily be made to hold water, a 
roof is under extraordinarily disadvantageous 
conditions because of the rays of the sun. 
Usually, therefore, a tar and gravel or other 
form of roof covering must be provided. 

CONSTRUCTION. 

The details of construction are treated at 
length for individual buildings in the chapters 
which follow. Chapter XX also takes up many 
special points and treats as well of different 
methods of reinforcing. 

A reinforced concrete building must have care¬ 
ful inspection while in process of erection, the 
special points to be observed being: 

(1) Exact proportioning of materials. 

(2) Mixing to a consistency only wet enough 
to flow sluggishly. 

(3) Placing the concrete so as to prevent sep¬ 
aration of ingredients. 

(4) Placing concrete to avoid joints except 
where called for. 

(5) Exact placing and imbedding of the rein¬ 
forcement. 

( 6 ) Proper securing of the forms. 

(7) Maintenance of the forms in position 
until the concrete is sufficiently strong. 


21 


CHAPTER III—CONCRETE AGGREGATES 


The term “aggregate” includes not only the 
stone, but also the sand which is mixed with 
cement to form either concrete or mortar; in 
other words, it is the entire inert mineral mate¬ 
rial. This definition, now generally accepted, 
has replaced the one restricting the term to the 
coarse aggregate alone. It is the object of this 
chapter to enumerate the general principles 
which should be followed in the selection of sand 
and stone for mortar and concrete, and to de¬ 
scribe briefly the method of testing aggregates 
and determining proportions which the author 
has found to give good results in practice. 

At the outset it may be said that a concrete of 
fair quality, if rich enough in cement, can be 
made with nearly any kind of mineral aggregate, 
but there is, nevertheless, a wide variation in the 
results produced. For the fine aggregate, sand, 
broken stone, screenings, pulverized slag or the 
fine material from cinders may be used separately 
or in combination with each other. For the 
coarse aggregate, broken stone, gravel, screened 
gravel slag, crushed lava, shells, broken brick, or 
mixtures of any of these may be employed. How¬ 
ever, the very fact of the adaptability of con¬ 
crete to so wide a range of materials, every one 
of which really consists of a large class varying 
in size, shape and composition, tends to blind one 
to the economies which often may be affected 
and the improvement in quality which almost 
always will result by a careful selection and pro¬ 
portioning of the aggregates. 

In many cases, especially where the cost of 
Portland cement is low, it may be cheaper to use 
whatever materials are nearest at hand, and in¬ 
sure the quality of the concrete or mortar by 
making it excessively rich in cement. If the 
structure is small and of little importance this 
course is properly followed, but, on the other 
hand, if a large amount of concrete is to be laid, 
and especially if the process is to be carried on in 
a factory, as in concrete block manufacture, it 
pays from the standpoints of both quality and 
economy, to use great care in the selection of the 
aggregates, as well as of the cement, and to pro¬ 
vide means for maintaining uniformity. 

To illustrate the variation which different ag¬ 
gregates may produce even when they are mixed 


with cement in the same proportions, the author 
has selected a few comparative tests of mortar 
and concrete. 

EFFECT OF DIFFERENT AGGREGATES 
UPON THE STRENGTH OF MORTAR 
AND CONCRETE. 

Tests by Mr. Renp Feret*, of France, with 
mortar made from different natural sands, show 
a surprising variation in strength, which is evi¬ 
dently due simply to the fineness of the sand of 
which the different specimens are composed. 
Selecting from his results proportions l:2i/ 2 by 
weight—that is, 1 part cement to 2i/ 2 parts sand 
—and converting his results at the age of five 
months from French units to pounds per square 
inch, the average tensile strength of Portland 
cement mortar made with coarse sand is 421 
pounds per square inch, with medium sand 368 
pounds per square inch, and with fine sand 302 
pounds per square inch. In the crushing strength, 
usually the most important consideration, the 
difference is even more marked. In round num¬ 
bers at the age of five months the mortar of 
coarse sand gave 5,200 pounds per square inch; 
of the medium sand, 3,400 pounds per square 
inch, and of the fine sand 1,900 pounds per square 
inch. Note that the different sands were not 
artificially prepared, but were taken from the 
natural bank and correspond to those which 
every day are being used for concrete and mor¬ 
tar. 

The effect of different mixtures of the same 
kind of material is shown by tests made by the 
author in 1905.f By varying the sizes of the 
particles of the aggregates, but using in all cases 
stone from the same ledge and the same propor¬ 
tion of cement to total aggregate by weight, 
namely, 1:9 (or approximately 1:3:6), it was 
found possible to make specimens the resulting 
strengths of some of which were two and a half 
times the strength of others. 

GENERAL PRINCIPLES FOR SELECTING 
STONE. 

The quality of concrete is affected by the hard¬ 
ness of the stone, the shape of the particles, the 

♦Taylor & Thompson’s “Concrete, Plain and Reinforced,’’ 
page 136. 

tProceedings American Society of Civil Engineers, Vol. LIX, 
1907. jj 


22 


maximum size of the particles and the relative 
sizes of the particles. 

If broken stone is used, and there is an oppor¬ 
tunity for choice, the best is that which is hard; 
with cubical fracture; with particles whose 
maximum size is as large as can be handled in 
the work; with the particles smaller than, say 
% inch, screened out to be used’as sand; and 
with the sizes of the remaining coarse stone vary¬ 
ing from small to large, the coarsest predomi¬ 
nating. 

If gravel is used it must be clean. The maxi¬ 
mum size of particles should be as large as can 
be handled in the work; grains below % inch 
should be screened out to be used as sand, and 
the size of the stone should vary, with the 
coarsest predominating. 

As already stated, the size of the coarsest 
particles of stone should be as large as can be 
handled in the work. This is because the strength 
of the concrete is thereby increased and a leaner 
mixture can be used than with small stone. In 
mass concrete the stones if too large are liable 
to separate from the mortar, and a practical 
maximum size is 2 % or 3 inches. In thin walls, 
floors and other reinforced construction a 1-inch 
maximum size is generally as large as can be 
easily worked between the steel. In some cases 
where the walls are very thin a %-inch maxi¬ 
mum size is more convenient to handle. 

It is a little more trouble but always best 
to screen out the sand from gravel or the fine 
material from crushed stone, and then remix 
it in the proportions required by the specifica¬ 
tions, for otherwise the proportions will vary at 
different points, and one must use and pay for 
an excess of cement to balance the lack of uni¬ 
formity. 

If the gravel is used, it is absolutely essential 
that it shall be clean, because if clay or loam 
adheres to the particles the adhesion of the ce¬ 
ment will be destroyed or weakened. Tests of 
the Boston Transit Commission give an average 
unit transverse strength of 605 pounds per 
square inch for concrete made with clean gravel 
as against 446 pounds per square inch when made 
with dirty gravel. 

COMPARATIVE VALUES OF DIFFERENT 
STONE. 

Different stones of the same class vary so 
widely in texture and strength that it is impos¬ 
sible to give their exact comparative values for 


concrete. A comparison by the author of a large 
number of tests of concrete made with different 
kinds of stone indicates that the value of a broken 
stone for concrete is largely governed by the 
actual strength of the stone itself, the hardest 
stone producing the strongest concrete. This 
forms a valuable guide for comparing different 
stones. Comparative tests indicate that different 
stones in order of their value for concrete are 
approximately as follows: (1) Trap, (2) gran¬ 
ite, (3) gravel, (4) marble, (5) limestone, (6) 
slag, (7) sandstone, (8) slate, (9) shale, (10) 
cinders. Although, as stated above, the wide 
difference in the quality of the stone of any class 
makes accurate comparisons impossible—and 
this difficulty is increased by the fact that the 
proportions and age of the specimens affect their 
relative value—an approximate estimate drawn 
from actual tests gives the value for concrete of 
good quality sandstone as not more than three- 
fourths the value of trap, and the value of slate 
as less than half that of trap. Good cinders 
nearly equal slate and shale in the strength of 
concrete made with them. 

The hardness of the stone grows in impor¬ 
tance with the age of the concrete. Thus gravel 
concrete, because of the rounded surfaces, at the 
age of one month may be weaker than a concrete 
made with comparatively soft broken stone; but 
at the age of one year it may surpass in strength 
the broken stone concrete, because as the cement 
becomes hard there is greater tendency for the 
stones themselves to shear through, and the hard¬ 
ness of the gravel stones thus comes into play. 
Gravel makes a dense mixture, and if much 
cheaper than broken stone, can usually be substi¬ 
tuted for it. 

A flat grained material packs less closely and 
generally is inferior to stone of cubical fracture. 

GENERAL PRINCIPLES FOR SELECTING 
SAND. 

The only characteristic of sand which need be 
considered are the coarseness of its grains and 
its cleanness. These qualities affect the density 
of the mortar produced, and therefore the test 
of the volume of mortar, or “yield” determines 
which of two or more sands is best graded. The 
“yield” or “volumetric” test is considered by the 
author of greater value for quick results than 
all others put together. The methods of em¬ 
ploying it are described farther along in the 
paper. 


23 


The best sand is that which produces the small¬ 
est volume of plastic mortar when mixed with 
cement in the required proportions by weight. 

A high weight of sand and a corresponding 
low percentage of voids are indications of coarse¬ 
ness and good grading of particles; but because 
of the impossibility of establishing uniformity 
in weighing or measuring, they are merely gen¬ 
eral guides which cannot under any conditions 
be taken as positive indications of true relative 
values. The various characteristics of sand are 
separately considered in the following para¬ 
graphs : 

WEIGHT OF SAND.—A heavy sand is gen¬ 
erally denser, and therefore better than a light 
sand. However, this is not a positive sign of 
worth, because the difference in moisture may 
affect the weight by 20 per cent., and when 
weighed dry the results are not comparable for 
mortars since fine sand takes more water than 
coarse. 

As an illustration of the variation in weight 
of natural sands having different moisture, the 
author found that the weight per cubic foot of 
Cowe Bay sand, which dry averaged 103 pounds, 
when placed out of doors and after a rain shov¬ 
eled into a measure and weighed in exactly the 
same way (although it was allowed to drain for 
two days) averaged 83 pounds. 

VOIDS IN SAND.—The voids, like the weight, 
are so variable in the same sand, because of dif¬ 
ferent percentages of moisture and different 
methods of handling, that their determination is 
of but slight value. In the Gowe Bay sand just 
mentioned, the voids were 38 per cent in the 
sand, dry, and 52 per cent in the same sand, 
moist. 

Because of such discrepancies, the author pre¬ 
fers to mix the sand with the cement and water, 
and determine the voids in the fresh mortar, as 
described later. This gives a true comparison 
of different sands, since with the same percent¬ 
age of cement, the mortar having the lowest air 
plus water voids is the strongest. 

COARSENESS OF SAND.—A coarse sand 
produces the densest, and, therefore, the strong¬ 
est mortar or concrete. A sufficient quantity of 
fine grains is valuable to grade down and reduce 
the size of the voids, but in ordinary natural ma¬ 
terial, either sand or screenings, there will be 
found sufficient fine material for ordinary pro¬ 
portions, such as 1:1, 1:2, or 1:2^>. For leaner 
proportions, such as 1:4 or 1:5, and sometimes 


1:3, an addition of fine particles will be found 
advantageous to assist the cement in filling the 
voids. A dirty sand, that is, one containing fine 
clay or other mineral matter, up to say, 10 per 
cent, is actually found by tests to be better than 
a clean sand for lean mortars. 

For water-tight work it is probable that a 
larger proportion of very fine grains may be em¬ 
ployed than for the best results in strength. 
This is a question, however, which has not yet 
been thoroughly investigated. 

Feret’s rule for sand to produce the densest 
mortar is to proportion the coarse grains as 
double the fine, including the cement, with no 
grains of intermediate size. There is difficulty 
in an exact practical application of this rule, but 
it indicates the trend to be followed in seeking 
maximum density and strength. 

CLEANNESS OF SAND.*—An excess of fine 
material or dirt, as has just been noted, weakens 
a mortar which is rich in cement. It may also 
seriously retard its setting. The author’s atten¬ 
tion was recently called to a concrete lining, one 
portion of which failed to set hard for several 
weeks, although the same cement was used as on 
adjacent portions of the work. The difficulty 
proved to be due entirely to the fact that the 
contractor substituted, in this place, a very fine 
sand, the regular material happening to run 
low. 

SHARPNESS OF SAND.—Notice that the 
quality of sharpness has not been mentioned 
among the essential characteristics of sand. This 
omission was intentional. Many specifications 
still call for “sharp” sand, and yet the writer has 
never known a sand to be rejected simply because 
of its lack of sharpness. As a matter of fact, if 
two sands have the same sized grains, and con¬ 
tain an equal amount of dust, the one with 
rounded grains is apt to give a denser and 
stronger mortar than the sharp grained sand. 
A sand with a sharp “feel” is preferable to an¬ 
other, not to any extent because of its sharpness, 
but because the grittiness indicates a silicious 
sand which is apt to have no excess of fine 
material. 

SAND VS. BROKEN STONE SCREENINGS. 
—Many comparative tests of sand and screen¬ 
ings have been made with contrary results. 
While frequently crusher screenings produce 
stronger mortar than ordinary sand, the author 

•The danger of vegetable impurities and the necessity for 
tensile tests referred to on page 13. See also page 26. 


24 



in an extensive series of tests has found the re¬ 
verse to be true. This disagreement is probably 
due to the grading of the particles, although in 
certain cases the screenings may add to the 
strength because of hydraulicity of the dust 
when mixed with cement. 

TESTING SAND. 

Previous paragraphs show the defects in the 
more common methods of examining sand. 

Tests made by the author in 1903 proved the 
value of the principles of the density of mortars 
laid down by Feret, and in the winter of that 
year similar plans for testing aggregates were 
introduced by Mr. William B. Fuller and the 
author at Jerome Park Reservoir, New York 
City. The object of the test is to determine 
which of two or more sands will produce the 
denser, and therefore the stronger, mortar in any 
given proportions. 

The different results in strength which Mr. 
Feret found with coarse, medium and fine sand 
respectively have already been given, these rela¬ 
tive strengths in compression being respectively 
5,200, 3,400 and 1,900 pounds, with proportions 
1:214 by weight in each case. An examination 
of the tests shows that the strongest mortar 
was also densest; that is, the smallest volume or 
yield of mortar was produced with a given weight 
of aggregate. 

The mortar of medium sand occupied a volume 
714 per cent in excess of the volume of the 
mortar with coarse sand; and the mortar of fine 
sand, a volume 17 per cent in excess of the 
mortar with coarse sand. 

Following these principles, two sands may be 
compared and the better one selected by de¬ 
termining which produces the smallest volume 
of mortar with the given proportions by weight. 
Using the method described below, the author 
has been able to increase the strength of a mortar 
about 40 per cent by merely changing the sizes 
of grains of the aggregate. 

The method of making the test is as follows: 
If the proportions of the cement to sand are by 
volume, they must be reduced to weight propor¬ 
tions; for example, if a sand weighs 83 pounds 
per cubic foot moist, and the moisture found by 
drying a small sample of it at 212° Fahr. is 4 
per cent, which corresponds to about 3 pounds 
in the cubic foot, the weight of dry sand in the 
cubic foot will be 83 — 3 = 80. If the propor¬ 
tions by volume are 1:3, that is, one cubic foot dry 


cement to 3 cubic feet of moist sand, and if we 
assume the weight of the cement as 100 pounds 
per cubic foot, the proportions by weight will be 
100 pounds cement to 3 X 80 = 240 pounds of 
sand, which correspond to proportions 1:2 4/10 
by weight. 

A convenient measure for the mortar is a glass 
graduate, about 11/2 inches in diameter, gradu¬ 
ated to 250 cubic centimeters. A convenient 
weight of cement plus sand, for a test, is 350 
grams. For weighing, the author employs Har¬ 
vard Trip scales, which weigh with fair accuracy 
to one-tenth of a gram. The sand is dried and 
mixed with cement, in the calculated proportions, 
in a shallow pan about 10 inches in diameter and 
1 inch deep. The mixing is conveniently done 
with a 4-inch pointing trowel. The dry mixed 
material is formed into a circle, as in mixing 
cement for briquets, and sufficient water added 
to make a mortar of plastic consistency, similar 
to that used in laying brick masonry. After mix¬ 
ing five minutes, the mortar is introduced about 
20 c.c. at a time into the graduate, and to expel 
any air bubbles, is lightly tamped with a round 
stick with a flat end. The mortar is allowed to 
settle in the grduate for one or two hours until 
the level becomes constant, when the surplus 
water is poured off, and the volume of the mortar 
in cubic centimeters is read. For greater exact¬ 
ness, a correction may be introduced for mortar 
remaining on pan and trowel. The other sands, 
which are to be compared with this one, are then 
mixed with cement in the same proportions by dry 
weight, and sufficient water added to give the 
same consistency. The percentage of water re¬ 
quired will vary with the different aggregates, 
the finer sand requiring the more water. After 
testing all the mortars, the sand which produces 
the strongest mortar is immediately located as 
that in the mortar of lowest volume. By syste¬ 
matic trials, the best mixture of two or more 
sands may also be found. 

In some cases a correction must be introduced 
for the specific gravity of the sand; for example, 
ordinary bank sand has an average specific grav¬ 
ity of 2.65, but if this is to be compared with 
broken stone screenings having a specific gravity 
of, say, 2.80, the proportions of the two must be 
made slightly different. For these particular 
specific gravities, proportions 1:3, by weight, 
with sand, correspond in absolute volume to pro¬ 
portions 1:3 2/10, by weight, of the screenings. 

In making these tests, it is also important to 
notice the character of the mortar as it is being 


25 


mixed. It should work smooth under the trowel 
and be practically free from air bubbles. 

TESTING SANDS FOR ORGANIC IMPURITIES 

The Colorimetric Test for Sand, developed by 
the Structural Materials Research Laboratory,* 
Lewis Institute, Chicago, is for the purpose of de¬ 
termining the amount of organic impurities in 
sand. It is not intended as a test for the grading 
or granulometric composition of the sand. 

The following is an extract from the Circular 
of the Lewis Institute describing the test, of 
which only the Field Test is given here: 

“A sample of sand is digested at ordinary tem¬ 
perature in a solution of sodium hydroxide 
(NaOH). If the sand contains certain organic 
materials, thought to be largely of a humus 
nature, the filtered solution resulting from this 
treatment will be found to be of a color ranging 
from light yellow up through the reds to that 
which appears almost black. The depth of color 
has been found to furnish a measure of the effect 
of the impurities on the strength of mortars 
made from such sands. The depth of color may 
be measured by comparison with proper color 
standards.” 

“Two methods of procedure have been de¬ 
veloped: (1) For Field Tests; (2) For Labora¬ 
tory Tests. 

“METHOD FOR FIELD TESTS. 

“Fill a 12-oz. graduated prescription bottle to 
the 41 / 2 -oz. mark with the sand to be tested. Add 
a 3 per cent solution of sodium hydroxide until 
the volume of the sand and solution, after shak¬ 
ing, amounts to 7 oz. Shake thoroughly and let 
stand over night. Observe the color of the clear 
supernatant liquid. 

“In approximate field tests it is not necessary 
to make comparison with color standards. If the 
clear supernatant liquid is colorless, or has a light 
yellow color, the sand may be considered satis¬ 
factory is so far as organic impurities are con- 

*Under the auspices of Committee C-9 of the American 
Society for Testing Materials. 


cerned. On the other hand, if a dark-colored solu¬ 
tion, ranging from dark reds to black, is obtained 
the sand should be rejected or used only after it 
has been subjected to the usual mortar strength 
tests. 

“Field tests made in this way are not expected 
to give quantitative results, but will be found 
useful in: 

“(1) Prospecting for sand supplies; 

“(2) Checking the quality of sand received on 
the job; 

“ (3) Preliminary examination of sands in the 
laboratory. 

“An approximate volumetric determination of 
the silt in sand can be made by measuring or esti¬ 
mating the thickness of the layer of fine material 
which settles on top of the sand. The per cent 
of silt by volume has been found to vary from 
1 to 2 times the per cent by weight.” 

TESTING CONCRETE AGGREGATES. 

For concrete in any given proportions, the best 
sizes of stone and of sand may be determined by 
similar methods to those described for testing 
sand mortars, although larger quantities of ma¬ 
terials must be used and the measure must be 
strong to withstand the light ramming which is 
necessary. A short length of cast iron pipe, 
closed at one end, may be used for this. 

The aggregates, which mixed with cement in 
the required proportions produce the smallest vol¬ 
ume of concrete, are usually the best, although, 
as already indicated, the shape of the particles 
and their hardness must also be taken into con¬ 
sideration. 

PROPORTIONING CONCRETE. 

A general principle of practical use in de¬ 
termining the relative proportions of two or more 
aggregates in a concrete is that, the weight of 
material and the percentage of cement remain¬ 
ing the same, the mixture producing the smallest 
volume of concrete is the best. 


26 



Fig. 4.—Carter’s Ink Factory, Cambridge, Mass. Densmore & LeClear, Boston, Architects; Aberthaw Construction 

Co., Boston, Contractors. 


PLANT OF CARTER’S INK COMPANY 


The new plant of the Carter’s Ink Company, 
Cambridge, Mass., located on a lot facing the 
Charles River, is an illustration of the archi¬ 
tectural possibilities of reinforced concrete in 
factory construction. A large majority of con¬ 
crete factories have been built with no regard 
whatever to appearance, when with a compara¬ 
tively small increase in cost it is possible to pro¬ 
duce an artistic structure. In the present case 
the location of the plant on the future Charles 
River parkway demanded a careful architectural 
treatment. 

Reinforced concrete was chosen on account of 
its adaptability to architectural design, its econ¬ 
omy for the loads required, its fireproof qualities, 
rapidity of erection, and freedom from vibration. 

The plant includes a main building for the 
manufacture and storage of the company’s prod¬ 
ucts, an external toilet room and stairway tower, 
a power house, and a glass storage building. 

The main building (shown in Fig. 4) is an L- 


shaped structure, four stories high, with a maxi¬ 
mum length of 186 feet, a height of 78 feet and 
an average width of 64 feet. The one-story 
power house is also of reinforced concrete, 69 
feet long and 41 feet wide. The glass storage 
building, 83 feet long and 61 feet wide, is a one- 
story frame structure with exterior walls of 
plaster on wire-lath and concrete floor. 

EXTERIOR DESIGN. 

In order to gain an architectural effect in keep¬ 
ing with the prominent location of the building, 
the front and sides were designed with recessed 
window arches, and variations in window group¬ 
ing, and trimmed with cast ornamental work and 
a cornice of quite elaborate design. Winchester 
gravel was used in the concrete panels and piers, 
the face being hand picked with smooth draft 
lines on the various panels to give the proper 
contrast between the component parts of the 
front and sides. 


27 



































REINFORCED CONCRETE DESIGN. 

The company’s work imposed heavy floor loads 
and somewhat longer spans than usual in mill 
construction. The total dead and live loads used 
in the design were: Basement, 200 pounds per 
square foot; first floor, storage division, 485 
pounds; offices, 150 pounds; lavatory and locker 
rooms, 125 pounds; second floor, 240 pounds; 
third and fourth floors, 355 pounds; fourth 
mezzanine, 320 pounds. 

In general, Johnson corrugated bar girder 
frames were used for reinforcement, the tensile 
stress allowed being 16,000 pounds per square 
inch. 


The concrete for the slabs and girders was 
mixed in the proportions of 1 part Atlas Port¬ 
land Cement to 2 parts sand to 4 parts broken 
stone passing a 1 -inch mesh, while the column 
mixture was 1 : 114 : 3 . In the beams and slabs a 
fibre stress of 600 pounds per square inch was al¬ 
lowed, and the columns were figured on the basis 
of 600 pounds per square inch in compression. 

All curtain walls, and also the basement retain¬ 
ing wall, were 1 :2^4:5 mixture with an addition 
of 1 part hydrated lime to 10 parts of cement, to 
make it more water-tight. 

A typical first-floor girder is shown in detail in 
Fig. 5. These girders have 20-foot spans and are 
spaced 10 feet 6 inches on cen¬ 
ters. They are 20 inches wide 
and 32 inches deep, reinforced 
with five 114 -inch and four 
li/ 8 -inch bars. Four of the 
114 ,-inch bars are bent up at 
the quarter points and carried 
over the support. Each girder 
has twenty-four 14 -inch V 
stirrups spaced as shown. 

The floor slabs are 714 
inches thick, reinforced with 
%-inch bars spaced 5 % inches 
apart. 

The photograph in Fig. 6 of 
the interior of the basement 
shows the columns and floor 
system. 

The columns throughout 
are reinforced with four 1 - 
inch and two %-inch bars, 
with 14 -inch hoops 12 inches 
on centers. 

Fig. 7 shows the form work 
and reinforcement in place for 
the second-floor construction. 

FOUNDATIONS. 

The foundation soil is filled 
land on clay, silt and streaks 
of sand, and about 200 spruce 
piles averaging 20 feet in 
length and 10 inches in di¬ 
ameter at the top were re¬ 
quired to carry the buildings. 
Each pile was figured to carry 
ten tons. 



Fig. 5.—Details of Typical Girder and Main Column Footings. 



Fig. 6.—Interior of Basement, Carter’s Ink Factory. 


The footings for the main 


28 

























































































columns, of which a typical 
design is shown in Fig. 5, are 
of the spread type, each rest¬ 
ing upon 24 piles placed 24 
inches apart on centers and in 
rows, 30 inches apart. In 
general the foundations are 
of the cut pyramid form and 
heavily reinforced. 

The basement curtain walls 
are carried from footing to 
footing, being reinforced as 
girders with horizontal bars 
to carry their own load and 
also with vertical bars to act 
as retaining walls. 

COST. 



The total cost of the plant 
was about $160,000. The 
forms for the columns cost 18 
cents per square foot of surface and for the 
floors 11 cents per square foot of superficial sur¬ 
face. The concrete for the beams and floor slabs 


Pig. 7.—View of Carter’s Ink Factory During Construction. 

cost $6.20 per cubic yard and for the columns 
$7.25 per cubic yard, while the reinforcing steel 
cost $41 per ton in place. 





KETTERLINUS BUILDING, PHILADELPHIA 


The plant of the Ketterlinus Lithographic 
Manufacturing Company is located in Philadel¬ 
phia at the northwest corner of Fourth and Arch 
Streets, and the reinforced concrete portion of 
the structure built in 1906 represents a type of 
building adapted to city manufacturing estab¬ 
lishments limited to a comparatively small 
ground area. The building illustrated on a fol¬ 
lowing page as Fig. 9 is eight stories high besides 
the basement, and its dimensions are 80 by 67 
feet. The architects and engineers were Bal¬ 
linger & I*errot, of Philadelphia, and they also 
supervised the erection, which was done by day 
labor with no general contractor. 

This new building adjoins and forms a part 
of the old plant of the Ketterlinus Company, 
which is of steel frame construction, fireproofed 
with terra cotta. 

In both buildings heavy machinery is now 



Fig. 8.—Typical Floor and Roof Plans of the Ketterlinus Building. 


running, and many large printing presses are at 
work on the third, fourth and fifth floors. Be¬ 
cause of the proximity of the old and new types 
of construction the advantages of the reinforced 
concrete, from the point of view of the manufac¬ 
turer, are particularly evident. In the building 
of steel and terra cotta construction the vibration 
from the machinery is noticeable as soon as one 
enters, while on the other hand, in the new struc¬ 
ture the concrete, because of its greater mass 
and inertia, absorbs the vibrations, and it is dif¬ 
ficult to appreciate the speed and power of the 
machines. As a result, too, of this reduction in 
the vibration the noise of the machinery is effec¬ 
tually deadened. 

The building is designed for a working load 
of 400 pounds per square foot. The concrete for 
practically the whole of the work was propor¬ 
tioned 1:21/4:5, equivalent by actual measure¬ 
ment to one barrel (4 bags) 
Atlas Portland cement to 
91/2 cubic feet of sand to 19 
cubic feet broken stone, the 
basis of proportioning is in 
a barrel of 3.8 cubic feet. 
The sand was well graded 
coarse material, frequently 
termed in the region of 
Philadelphia “Jersey grav¬ 
el” ; the stone was trap 
rock broken to a size at 
which all the particles 
would pass a one-inch ring 
excepting the stone in the 
concrete immediately sur¬ 
rounding the steel, which 
was of a size to pass 
through a half-inch ring. 

To harmonize with the 
old adjoining building of 
which it forms a part, the 
exterior walls are faced 
with brick with terra cotta 
trimmings. 


DESIGN. 

Several features in the 
design of the Ketterlinus 
building are of unusual in¬ 
terest. The columns below 
the fifth floor, instead of be¬ 
ing the usual solid concrete 


30 






























































































































construction with four or more round rods for re¬ 
inforcement, are essentially steel columns sur¬ 
rounded by concrete. The beams and girders 
are reinforced with the unit frame system in 
which the steel is all put together in the shop 
and brought to the job ready to place in the 
form. The saw-tooth roof is also a novel feature 
for reinforced concrete. 

The columns are spaced 13 feet 6 inches apart 
in one direction and 19 feet 2 inches in the other. 
The girders follow the shorter span, and the bays 
are divided into three panels by the cross beams, 
as shown in Fig. 8. 


COLUMNS. 

One of the problems in con¬ 
crete building construction 
where the loads are heavy or 
the building is several stories 
high, is to build the columns 
small enough to satisfy the 
requirements of the occupants 
and owners without overload¬ 
ing the concrete. Its solution 
is especially difficult in a city 
building where the land area 
is so valuable that every 
square inch of floor space is at 
a premium, and where there 
must be more stories than are 
economical under other condi¬ 
tions. Moreover, the building 
laws of many cities require 
more conservative loading 
than might be warranted if it 
were certain that the condi¬ 
tions of construction were in 
all cases the best. 

In a number of recent in¬ 
stances the difficulty has been 
met by the use of composite 
columns, a combination of 
concrete and structural steel, 
and this is the plan followed 
by the designers of the Ketter- 
linus building. Full details of 
the column construction are 
presented in Fig. 10. 

The interior columns in the 
building up to the fifth floor 
are 23 inches in diameter. In 
the basement and the four 
lower stories, the core of the 
column is formed of steel 
plates and angle irons riveted 


together in the form of a cross. Around this 
cross Y8 inch wire ties were placed every 12 
inches and looped around four vertical round rods 
which increased the reinforcement. In the base¬ 
ment, for example, the center steel is made up 
of a plate 18 inches wide and % inch thick with 
two plates of similar thickness but 8 inches wide 
at right angles to it, and four angle irons 6 by 6 
by % inch all riveted together. The four round 
rods, which complete the so-called “Star” rein¬ 
forcement, are 1 l/g inch diameter. 

The columns in the three stories nearest the 
top are designed to carry the full dead and live 
loads of floors and roof. In each lower story the 
columns are designed to carry the full dead load 


Fig, 

Architects 


9.—The Ketterlinus Building. (See p. 30). 
and Engineers, Ballinger & Perrot of Philadelphia. 
31 














and a smaller proportion of the full live load than 
can be carried by the floor construction, this live 
load factor being reduced proportionately to the 
number of floors carried; for example, the base¬ 
ment columns were calculated on a basis of car¬ 
rying on the steel cores alone three-fourths the 
live load plus the full dead load with a factor of 
safety of 4. 

The steel is designed to bear the computed 
load without exceeding a maximum compression 
of 16,000 pounds per square inch. The compres¬ 
sive strength of the concrete in these columns is 
not considered, though almost sufficient to carry 
the dead load. 

The weight of the girders is borne in part by 
brackets of steel riveted to the angle irons and 
partly by the concrete knees or enlargements of 
the columns which run out obliquely from the 
columns and which are reinforced on each side by 
two i/^-inch rods. 

Above the fourth 
story the columns 
are of the same 
diameter but with 
the more ordinary 
reinforcement of 
four round rods. 

FLOOR SYSTEM 

Each girder was 
designed as an in¬ 
dependent beam 
supported at the 
ends by the enlarge¬ 
ment of the col¬ 
umns and the steel 
brackets. The area 
of the reinforcing 
steel was calculated 
in the usual way, 
but instead of plac¬ 
ing each rod sep¬ 
arately in the form, 
girder frames were 
made from quad¬ 
ruple or twin web¬ 
bed bars, which 
were cut, bent to 
shape and stirrups 
fastened thereto in 
the shop. The girder 
frame reinforce¬ 
ment was brought 
to the building in 
the form of a truss, 


and the work of placing consisted simply of set¬ 
ting this truss in the form upon cast steel 
sockets, each having a %-inch threaded stud pro¬ 
jecting upward through the frame. A nut 
screwed down on this stud over the frame holds 
it rigidly in position. Every rod and every mem¬ 
ber could not help but be in exactly the right 
location in the beam. This girder frame and 
socket were the invention of Emile G. Perrot, one 
of the firm of architects who designed the build¬ 
ing, the object being to insure the exact amount 
and arrangement of tension and shear members 
in the exact location as designed, and to afford 
opportunity for inspection of the steel in posi¬ 
tion before the pouring of the concrete. 

In the various plans the letter “Q” is entered 
as a part of the description of the reinforcement. 
This stands for the word “Quadruple” and indi¬ 
cates a group of four rods held at intervals by 



Fig. 10.—Details of Columns and Girders. 


32 

























































































































































special sockets. 

The rods are rolled in sets of four, connected 
by a web, and this web is sheared and bent down 
in 2 -inch lengths at intervals of 3 inches to give 
greater grip in the concrete. These 2-inch 
lengths are bent back over stirrups, where they 
occur, to clinch them in position on the frame. 
The outside bars are also cut loose at each end 
and bent upward to reinforce the top of the beam 
near the supports. The sockets (Fig. 10.) are 
shaped so that they support the rods iy 2 inches 
above the bottom the beam or girder, and are 
held in place by a %-inch bolt passing up through 
the bottom of the wood mold. These threaded 
sockets afterward are used for securing shaft¬ 
ing, hangers or other fixtures. 

In the various dimensions of beams on the plan, 
the width and depth is given first, followed by 
“1 Q” or “2 Q” (the latter meaning 8 rods), then 
the diameter of rod, and finally the thickness of 
the web forming a part of the rods. Thus 
10"xl8"-2Q%"xl / 4" means that the beam is 10 


inches wide by 18 inches deep, reinforced with 
two groups of four rods % inch diameter, con¬ 
nected longitudinally by webs 14 inch thick. The 
depth of the beams and girders is given from the 
under side of the slab instead of from the top of 
the slab, the more usual form. The area of cross- 
section of each of such “Q” bars is about 3 
square inches. 

The slabs are of usual construction, being 4 
inches thick and reinforced for the net span of 
3 feet 10 inches with 3-inch No. 10 expanded 
metal, this mesh having been substituted instead 
of %-inch rods spaced 6 inches apart and occa¬ 
sional 14 -inch rods running in the other direc¬ 
tion, as originally shown on the drawings, at an 
increase of about one per cent of the cost of the 
building. 

The wearing surface is a l^-inch maple wood 
floor on 2 by 4-inch sleepers 16 inches apart. The 
sleepers are placed on the concrete slab and cin¬ 
der concrete in proportions 1 : 3:7 filled in be¬ 
tween them. 

WALLS. 

The walls are essen¬ 
tially reinforced concrete 
columns, veneered on the 
outside with 4 inches of 
brickwork and separat¬ 
ing the windows. The 
window lintels are of 
concrete faced with terra 
cotta to match the red 
sandstone of the older 
building adjoining and 
anchored to the concrete. 
The lintels form rein¬ 
forced concrete beams 
and support a brick wall 
13 inches thick, which is 
run up to the bottom of 
the terra cotta window 
sills. 

The method of con¬ 
necting the brick with 
the concrete of the col¬ 
umns is shown in Fig. 11 , 
copper wall ties y 16 by % 
by 7 inches being set in 
the concrete at intervals, 
and, after the removal of 
the forms, bent out and 
laid into the joint of the 
face brick, which is sep¬ 
arated from the concrete 



Fig. 11—Brick Wall Ties. 



S3 


















































Fig. 13—Interior of Ketterlinus Building, Showing 20-Ton Lithographic Press. 


by a %-inch mortar joint for purposes of align¬ 
ment. 

ROOF. 

The general design of the saw-toothed roof 
appears on the full cross-section, Fig. 12. In 
Fig. 12 the details are illustrated. Inclined gird¬ 
ers extend across the building,, and above these 
project the sawteeth, which rest upon concrete 
beams running into the girders. Saw-tooth con¬ 
struction in reinforced concrete is, of course, 
expensive, because of the irregularities of the 
forms, but with the aid of the unit reinforcing 
system, which accurately locates the steel, the 
design is satisfactorily worked out. 

As in the other plans, the letter “Q” indicates 
a quadruple bar whose web thickness is desig¬ 
nated by the final fraction in the dimensions. In 
the roof, instead of the four bars being on one 
plane and rolled all together with a single web, 
they are arranged in pairs, with a web connect¬ 
ing the two bars of each pair. 


COST. 

The concrete portion of the building cost 
$27,000. This sum included the form work and 
steel reinforcement, except the column cores and 
grillage beams, which cost $5,500 additional. The 
total cost of the structure, including the inside 
finish, amounted to nearly $90,000. 

The unit girder construction is somewhat more 
expensive than the ordinary system of bending 
and placing separate rods, but the result is a sure 
location for every member, with no danger of a 
rod being left out or placed so high as to lose a 
large part of its efficiency. In this particular 
building the cost of the unit girder reinforce¬ 
ment was 4 cents per pound after bending ready 
to place. 

INSURANCE. 

It is of interest to observe that the building is 
insured by the Associated Mutual Insurance 
Companies, and at the time of completion was the 
only building in the congested portion of Phila¬ 
delphia which was insured by them. 


34 















Fig. 14.—Exterior of Spinning Mill, Maverick Cotton Mills, East Boston, Mass. 
Engineers and Architects, Lockwood, Greene & Co. of Boston. 


MAVERICK COTTON MILLS 


The Maverick Mills, located at East Boston, 
Mass., were the first textile mills of large size in 
the United States to be built entirely of rein¬ 
forced concrete. While ultimately the mills will 
operate 250,000 spindles, the initial installation 
is about one-quarter of this, and consists of a 
51,200-spindle mill, 550 feet long, 130 feet wide, 
two stories in height, a 340 by 231 feet weave 
shed, one story high; a 30 by 40 feet two-story 
detached office building and a 91 by 62 feet power 
house adjoining the weave shed. 

The problem of installing the textile machin¬ 
ery on the concrete floors proved to be compara¬ 
tively simple of solution, and it was found that 
the equipment could be set up fully as cheaply 
and with scarcely any more trouble than in a mill 
with wooden floors. This is partly due to the 
fact that the absence of vibration and the greater 
friction between the bases of the machines and 
the concrete floor almost precluded any tendency 
for the machines to “creep,” which allowed a 
material reduction in the number of floor bolts. 


In the case of the spinning frames, for example, 
instead of the 22 floor bolts usually needed, but 
six were required, and by using an air drill and 
expansion bolts these six could be placed almost 
as rapidly as six lag screws in a wooden floor. 

The exterior of the spinning mill is shown by 
the photograph in Fig. 14. 

The plant was designed by Lockwood, Greene 
& Co., Engineers and Architects, :of Boston, 
Mass., and was built under their supervision ac¬ 
cording to the Hennebique System of reinforced 
concrete by the Hennebique Construction Com¬ 
pany of New York. 

Reinforced concrete was used throughout the 
entire plant, the concrete being mixed in the 
proportions of 1:2:4. The stresses assumed in 
computing the sizes of the various members were 
650 pounds per square inch extreme fibre stress 
on the concrete, and 16,000 pounds per square 
inch tension in the steel, the ratio of the 
modulus of steel to that of concrete being taken 
as 15. 


35 . 




























Fig. 15—Interior View of Spinning Mill, Maverick Cotton Mills. 


SPINNING MILL. 

In the spinning mill, which was designed to 
carry a live load of 75 pounds per square foot, 
the columns are spaced in rows 25 feet apart 
transversely and 10 feet 8 inches longitudinally. 
The story heights are 16 feet. The floor system 
consists of reinforced concrete girders spanning 
the 25 feet transversely from column to column 
and carrying a 41/4-inch floor slab of 10 feet 8 
inches span. 

Fig. 16 shows the detailed design of a typical 
girder. These girders were designed as fully 
continuous, the bending moment at both the cen¬ 
ter and over the supports being taken as M 2 wl 2 . 
In order to provide for the excess compression 
in the concrete at the bottom of the girder at 
the support, caused by the continuous action, the 
girders were made deeper next to the support 
by forming a flat haunch as shown in Fig. 16. 
The girders are reinforced with two 1 14 -inch 
and two 1%-inch round rods, the 1 Vs-inch rods 
being bent up near the quarter points and carried 
horizontally over the supports into the adjacent 
bay. 

The stirrups, which are flat steel % inch by 


% inch, were bent in the form of a U and were 
placed as shown in Fig. 16. Near the support the 
stirrups were inverted because, in a continuous 
beam in the part near the support subjected to 
negative bending moment, the diagonal tension 
acts in the opposite direction to that in the part 
subjected to positive bending moment. 

The floor slabs, which are 414 inches thick, 
were also calculated with a moment of y 12 wl 2 
and are reinforced with %-inch rods, 6 inches on 
centers. Cross reinforcing consisting of three 
%-inch rods at right angles to the main rein¬ 
forcing is provided in each bay to prevent shrink¬ 
age and temperature cracks and to stiffen the 
floor. 

The floors are finished with a 1-inch granolithic 
surface, composed of 1 part cement to 1 part 
sand to 1 part Vi-inch stone, laid before the con¬ 
crete below it had set, so as to form one homo¬ 
geneous slab. 

All columns supporting the first floor are 18 
inches square, those on the second 16 inches 
square, and those running to the roof 14 inches 
square. The reinforcing for these columns con¬ 
sists of four %-inch rods bound with %-inch 


36 








by 3 /4-inch hoops spaced 12 
inches on centers. 

The photograph in Fig. 15 
illustrates the interior of the 
mill, and is especially inter¬ 
esting in showing the heavy 
motors and shafting at¬ 
tached directly to the con¬ 
crete above. 

WEAVE SHED. 

In the weave shed, which 
is only one story high with 
a basement, the columns are 
spaced 26 feet on centers 
longitudinally and 21 feet 4 
inches transversely, every 
other column being carried 
through the first floor to sup¬ 
port the roof construction. 

The floor, which is similar 
in design to that of the mill 
described above, was de¬ 
signed for a live load of 100 
pounds per square foot. 

A particularly interesting 
feature in the design of the 
weave shed is the saw-tooth 
roof construction shown in 
detail in Fig 17 and by the 
photograph in Fig. 19 of the 
interior of the building. 

The inclined girders were 
designed as simply supported 
and were proportioned so as 
to have sufficient stiffness to 
obviate the necessity of hori¬ 
zontal tie rods from bay to 
bay. 

The total rise of the saw¬ 
tooth is 9 feet 10 inches 
from the top of the column 
to the peak of the roof. 

All the saw-tooth sashes 
are fixed and are double 
glazed. A wooden stool is 
bolted to the concrete sill and 
and at the top a wooden 
blocking piece is attached 
continuously to the edge of 
the roof slab. The sash fits 
underneath this blocking 
piece and is attached to it by 
clamps and screws. The drip 
is taken care of by a beveled 



Fig. 16—Details of Typical Beam, Slaf) and Column. 



Fig. 17—Cross Section Detail of Saw-Tooth Roof. 



Fig. 18—Details of Saw-Tooth Sashes, Maverick Cotton Mills. 


37 





































































































facia board placed over the 
top of the blocking piece and 
the top rail of the sash. 

Interior condensation is 
handled by a galvanized iron 
gutter supported on wrought- 
iron straps screwed to the 
stool, thence discharging into 
a 2-inch pipe running the 
width of the building in each 
bay. The drawing in Fig. 18 
gives the detail design of the 
saw-tooth sashes. 

Three-ply asbestos asphalt 
built-up roofing was used, this 
roofing being brought over the 
peak of the saw-tooth and 
down over the facia board. 


POWER HOUSE. 

The power house also of 19 — Interior View of Weave Shed, Maverick Cotton Mills. 


reinforced concrete con¬ 
struction, is divided into two parts by a longi¬ 
tudinal wall, one part being a boiler room one 
story high and the other a basement and one 
story turbine room. 


The foundations of the boiler room are formed 
of wooden piles capped with reinforced concrete 
beams, while the engine-room foundation con¬ 
sists of a 22-inch reinforced concrete mattress. 



38 






REINFORCED CONCRETE STORAGE WAREHOUSE, LYNN, MASS. 


The Lynn Storage Warehouse, at Lynn, Mass., 
is built for the storage of general merchandise 
and furniture, reinforced concrete having been 
selected as the most economical fireproof con¬ 
struction. To provide for the variable character 
of its contents, the several floors are designed to 
sustain different loading; the three lower floors 
are each planned for the rather heavy loading of 
250 pounds per square foot, while on the fourth 
floor 200 pounds per square foot of loading is to 
be allowed, and on the fifth and sixth floors 150 
pounds. A possible weight of 50 pounds per 
square foot is provided for in 
the roof design. 

The building shown in Fig. 

20 is six stories high besides 
the basement, being 50 feet 
wide by 165 feet long. Al¬ 
though not strictly speaking a 
factory building, the design is 
typical of first-class factory 
construction. 

An interesting feature of 
the layout is the omission of 
the first floor in the corner of 
the building near the large 
elevator, in order to provide 
sufficient head room for teams 
to drive in and deposit their 
load upon the elevator, or else, 
if preferred, to drive directly 
onto the elevator, which is 
11 x12 feet in area, so that the 
wagon and horses can be 
elevated to the floor where 
the goods are to be placed 
and hauled to the proper 
point. 

A full cross-section of the 
warehouse, showing the di¬ 
mensions of the members and 
the general scheme of design, 
is shown in Fig. 21. 

FLOOR CONSTRUCTION. 

Round rods are used for 
reinforcement of the beams, 
girders and columns, while 
expanded metal forms the slab 
reinforcement. 

The designs were carefully 
worked up by the Eastern 


Expanded Metal Company and checked by Mr. 
Worcester as consulting engineer. The sec¬ 
tional view (Fig. 21) illustrates the gen¬ 
eral scheme of reinforcing. Complete details 
of a typical girder, beam and slab, designed to 
safely sustain 150 pounds per square foot of the 
floor load in addition to the weight of the con¬ 
crete, are drawn in Fig. 22. The slab, as indi¬ 
cated, is 6 feet in width from center to center of 
beam or 5 feet 3 inches in net span. The beams 
are 17 feet 9 inches from center to center of 
girders or 17 feet net span. The girders are 12 



‘V 


Fig. 20—Lynn Storage Warehouse. 

The Designer of the Reinforced Concrete and also the Builder Was the 
Eastern Expanded Metal Company of Boston, Mr. J. R. Worcester Being 
Consulting Engineer. The Architect Was Mr. D. A. Sanborn of Lynn. 


39 









feet between centers of columns or lO 1 ^ feet net 
span. 

The expanded metal reinforcement is placed 
near the bottom of the slab in the center of its 
span, and rises up to the top of the slab over the 
beams to provide for negative bending moment. 
The metal used is 3-inch mesh, No. 10 gage, this 
being equal to a cross-section of 0.175 square 
inches per foot of width of slab, or 0.5 per cent 
of the cross-section of the slab area above the 
steel. 


In the beams three 1-inch rods are imbedded, 
one of them bent up at the quarter points and 
running horizontally over the supports so as to 
lap by the rod from the next bay, thus giving 
two-thirds as much reinforcement over the sup¬ 
ports as in the center of the beam. The stirrups 
are flat steel 14 inch by 1 inch. Notice from 
Fig. 21 that in the three lower stories, where the 
loading is heavier, there are five stirrups in each 
end of the beam instead of two. The beams in 
these lower stories are made the same 
size, 9 inches by 20 inches, in order 
to use the same forms throughout the 
building, but the reinforcement is 
heavier. 

The typical girders in Fig. 22 have 
five %-inch rods at the center, two of 
them bent up and running on an in¬ 
cline from the center of the span. 
The incline starts at the center of the 
girder instead of one-quarter way 
from each end, because the girder 
having its greatest load at the center, 
the shear is nearly uniform through¬ 
out the entire span. 

Instead of the more usual practice 
of forming the wall girders as a part 
of the wall, they are built independ¬ 
ently of. the wall slab, as indicated in 
Fig. 21. 

FLOOR SPECIFICATIONS. 
There are several points of particu¬ 
lar interest in the floor specifications, 
and without copying them entire a 
brief outline is worth noting, as the 
data are quite full and the require¬ 
ments conservative. 

The slabs are calculated with a 
bending moment y 10 WL in cases 
where three or more slabs are con¬ 
tinuous, while for the wall slabs % 
WL is employed. The working 
strength of the concrete in compres¬ 
sion is limited in the slabs to 500 
pounds per square inch if computed 
by the parabolic method of stress, 
which is equal to about 600 pounds by 
the more usual straight line method. 
The slab steel is limited to 16,000 
pounds per square inch in tension, the 
ratio of the modulus of steel to that 
of concrete being taken as 15. At 
right angles to the length of the 
span y 10 square inch of steel is re- 



Fig. 21—Cross Section Through Lynn Storage Warehouse. 

40 





















































































































quired per foot of length of slab, which with the 
4-inch slab is equivalent to about 0.25 per cent. 
A thickness of % inch of concrete is required 
below the metal in the slabs. 

The bending moment in the beams and girders 
is considered as Ys WL. The beams are consid¬ 
ered as T-beams in computing their strength, and 
it is specified that the width of the flange shall 
not exceed one-third the span, and that the aver¬ 
age compression in the flange shall not exceed 
two-thirds of the extreme fiber stress. 

The vertical shear in the concrete in beams 
which are not reinforced for shear is limited to 
one-tenth the extreme compressive working 
stress in the concrete, and it is assumed that this 
vertical shear is distributed over a section whose 
area is the width of the stem, that is, the width 
of the beam multiplied by the distance from the 
center of the steel to the center of the slab, the 
latter being considered as approximately the 
center of compression. In any case even when 
the beam is reinforced for shear the unit shear 
stress is limited to three-tenths of the extreme 
compressive unit fiber stress. Thus, if the allow¬ 
able compressive fiber stress is 500 pounds per 
square inch, the shear in beams not reinforced 
for shear must not exceed 50 pounds, and in any 


case the section must be large enough so that 
even if reinforced there is sufficient area of con¬ 
crete to keep the total stress within a limit of 
150 pounds per square inch. 

When all of the shear cannot be taken by the 
concrete, the vertical component of the diagonal 
bent-up tension rods is figured to take it, and, in 
addition, if necessary vertical or diagonal stir¬ 
rups are introduced. 

The specifications required for the coarse ma¬ 
terial of the aggregate trap stone ranging in 
size of particles from Yi inch to 1^4 inches. The 
proportions for the floor system are 1:23/2 '-5, or 
by exact volume one barrel (4 bags) cement to 
10 cubic feet sand to 20 cubic feet stone. 

COLUMNS. 

The columns are spaced 12 feet apart length¬ 
wise of the building and 17 feet 9 inches on cen¬ 
ters across the building. The interior columns 
supporting the lower floors are 24 by 24 inches 
and 25 by 25 inches (the larger size supporting 
the greater spans), and in the three upper stories 
the sizes are reduced to 17 by 17 inches and 18 
by 18 inches. This arrangement was used to 
ayoid remaking the column forms, this saving, in 


41 




































































the opinion of the builders, being enough to more 
than offset the slight excess of concrete required. 

The columns are outlined in Fig. 22 and also 
quite distinctly in the general cross-section in 
Fig. 21. In the latter the diagonal rods will be 
noticed at the head of each column running into 
the beams and providing diagonal reinforcement 
against wind pressure. The building is so high 
in proportion to its width that this reinforcement 
was considered advisable. 

The ordinary reinforcement of the columns is 
four %-inch vertical rods, with occasional hoops 
inch in diameter. In the wall columns, which 


are oblong in plan and which because of their 
location are subjected to a greater wind pressure, 
four larger vertical rods are inserted. The rods 
are of such length as to project above the next 
floor level, and the next set rests upon this floor 
so as to lap and transfer the stresses. 

The columns are laid with a richer concrete 
than other parts of the building, being mixed 
in proportions 1:114:3. The compressive stress 
allowed is 700 pounds per square ipch figured on 
the area of the column, or 600 pounds per square 
inch on the concrete if the steel is computed to 
take a proportion of the compression. 


42 



Fig. 23—Loading Buildings, Winchester Repeating Arms Company. 


WINCHESTER REPEATING ARMS FACTORY 


The new loading buildings of the Winchester 
Repeating Arms Company, located on their prop¬ 
erty between Winchester Avenue and Sheffield 
Avenue, in New Haven, Conn., are especially in¬ 
teresting because of the heavy loads actually 
carried and the fact that flat-slab or girderless 
floors, sometimes called the mushroom system, 
were adopted instead of the ordinary plan of 
short-span slabs, supported by beams and girders. 

In this flat-slab construction, which is illus¬ 
trated by the photograph of the interior of the 
building in Fig. 26 and by the details of design 
in Fig. 24, no beams are used, the floor being of 
uniform thickness throughout and the loads 
transmitted from the floor slab direct to columns 
with flared capitals. The absence of the beams 
that tend to cut down the head room, obstruct 
light, gather dust, and interfere with the con¬ 
venient arrangement of the shafting arid pulley 
supports, goes far to make this for many pur¬ 
poses an ideal form of factory construction. 

The loading buildings are duplicates with the 


exception of a steel-frame plaster-walled storage 
room on the roof of one, and they are connected 
by a corridor opening off the elevator well and 
toilet rooms that serve both buildings. Each 
building is 300 feet long, 60 feet wide, two stories 
high and designed with sufficient strength to 
provide for two additional stories in the future. 

The photograph in Fig. 23 shows the completed 
buildings. 

DESIGN. 

The second and future third-story floors were 
designed to carry a live load of 250 pounds per 
square foot over the entire area, while the other 
floors throughout the buildings, including stairs, 
landings, platforms, etc., were designed for a live 
load of 10 pounds per square foot. 

The columns are spaced 20 feet by 24 feet on 
centers. 

All floor slabs are 10 inches thick and rein¬ 
forced by bands or sets of %-inch round rods 


43 












Fig. 24—Plan Showing Floor Reinforcement, Winchester 
Repeating Arms Loading Building. 

running in four directions radially from the col¬ 
umn heads. The spacing of these rods, together 
with the arrangement of the radial bars, is shown 
by the partial second-floor plan in Fig. 24. 

The end panels are supported by reinforced 
concrete beams running between the exterior 
columns. These beams, a typical one of which 
is shown in detail by Fig. 25, also carry the brick 
panel beneath the windows. 

In calculating the strength of the flat slab and 
of the wall beams the ratio of the modulus of 
elasticity of steel to that of concrete was taken 
as 15, the concrete was figured at 625 pounds per 
square inch fiber stress and the steel in tension 
at 14,000 pounds per square inch. 

The columns, shown in detail by Fig. 25, are 
composed of structural steel plate and angle col¬ 




Fig. 26—Interior of Leading Building, Winchester 
Repeating Arms Company 

umns incased in concrete. This structural steel 
work, designed to carry the entire live and dead 
loads of the floors above, together with the 
weight of the columns themselves, was com¬ 
puted on the basis of Gordon’s formula, which 
gave a stress of approximately 12,000 pounds per 
square inch. Fig. 25 shows the details of the 
flared column heads and the arrangement of the 
radial bars and circular hoops which support the 
slab reinforcement. 

Throughout the entire work the concrete was 
mixed in the proportions of 1 part Atlas Portland 
Cement to 2 parts sand to 4 parts broken stone. 

In the first story the finished floors are of 
1 ^-inch tongued and grooved maple flooring laid 
on 3 by 6-inch spruce planks bedded on “Tar- 
Rok.” The second story finished floors consist 
of 1%-inch tongued and grooved spruce plank 
secured to 3 by 3-inch spruce 
screeds placed 20 inches on 
centers and embedded in 3 
inches of cinder concrete fill. 

COST. 

The total cost of the build¬ 
ing, including excavation, 
was about $150,000. The 
cost of the concrete in place 
was $6.00 per cubic yard. 
The forms cost 12^ cents 
per square foot and the rein¬ 
forcing steel $45 per ton in 
place. 



44 

















































































Fig. 27—Bullock Electric Machine Shop. Ferro-Concrete Construction Company, Contractors. 


BULLOCK ELECTRIC MACHINE SHOP 


A novel feature of the reinforced concrete ma¬ 
chine shop of the Bullock Electric Company, at 
Norwood, Ohio, a branch of the Allis-Chalmers 
Company, is the supporting of 10-ton cranes 
upon concrete brackets which form a part of the 
concrete column. It is customary even in rein¬ 
forced concrete shops to place the crane runs 
upon steel columns independent of the rest of 
the structure, but we have here an example of 
the transmission of the load directly from the 
runways, which are steel plate girders, to the re¬ 
inforced concrete columns. The machine shop, 
illustrated in Fig. 27, was only fifty-eight and a 
half days in building and has been in successful 
and continuous operation since its completion. 

The building under consideration is an exten¬ 
sion to Shop No. 3, which is of the regular type 
of steel frame with brick walls. The extension 
was first designed in similar steel construction, 
but an alternate proposal to substitute reinforced 
concrete made by the Ferro-Concrete Construc¬ 
tion Company, of Cincinnati, was adopted at sub¬ 
stantially the same cost. 


Twisted steel was used for reinforcement. 
The proportions of the concrete were 1:2:4 
throughout, using 4 bags Atlas Portland cement 
to 8 cubic feet of good coarse sand to 16 cubic 
feet of broken stone, which was the run of the 
crusher, screened through 11,4-inch screen. 

The floors consist of three longitudinal bays 
running the entire length of the building, a dis¬ 
tance of 256 feet. The total width is 107 feet 
71/2 inches, thus allowing the two outer bays to 
be ""each 42 feet 111/2 inches and the inside bay 
21 feet 81/2 inches. In the other direction, that 
is, lengthwise of the building, the columns are 
16 feet apart on centers. The long open floor 
spaces afford ample room for the machine tools 
and the handling and distributing of the parts 
and the finished machines. A view of the shop 
in operation is photographed in Fig. 30. 

The height of the first story, 27 feet in the 
clear from the floor to the ceiling and 23 feet 
in the clear to the bottom of the girders, pro¬ 
vides the head room necessary for the 10-ton 
cranes which are located in the outside bays, 


45 






















and also permits very large high windows. 

The center bay is designed so that another 
crane may be installed there when required, but 
for the present its place is occupied by an inter¬ 
mediate floor. This floor is of light steel I-beam 
and wood construction, resting upon channel 
irons running across between the two rows of 
columns. The channels are bolted at the ends 
to the concrete columns and their weight also 
supported by straps suspended from the crane 
brackets. Had the floor been intended for per¬ 
manent use it would have been built of rein¬ 
forced concrete, but the difficulty and expense 
of tearing down a floor of concrete when the 
space was needed for the crane made this im¬ 
practicable. 

DESIGN. 

The general design of the building is shown in 
the cross-section in Fig. 28. 

The lower story is devoted to the manufacture 
of the heavier part of the electric machinery and 
in the assembling of dynamos. In the upper 
story are the lighter machine tools for the mak¬ 
ing of the smaller parts. The roof is of 2-inch 
plank upon steel trusses (see Fig. 28), being built 
in this way instead of in reinforced concrete so 


that it can be raised and a third story added 
when needed. One end of the building, as shown 
in the photograph of the completed shop, Fig. 27, 
is also of temporary construction, so that it can 
be lengthened without tearing down a brick and 
concrete wall. 

COLUMNS. 

Footings of the interior are shown in Fig. 29. 
These illustrate a typical reinforced concrete 
footing with two layers of rods at right angles 
to each other in the bottom. In this case the 
rods are %-inch diameter, while in the footings 
for the wall columns, which are not shown in 
our drawings, l/^-inch rods fulfil the require¬ 
ments. The rods in each layer are shorter than 
the dimensions of the footing in the interior col¬ 
umns (Fig. 29), being 6 feet 8 inches long and 
placed with one end 2 inches from the edge of 
the footing and the other end 18 inches from 
the opposite edge, the alternate rods being stag¬ 
gered to allow for the decrease in the bending 
moment from the column toward the edges of 
the footing. As the footing is square, while the 
column is oblong, 10 bars run in one direction, 
while 12 bars are placed in the other layer to 
provide for the greater bending moment. 


46 









































































The footings really ex¬ 
tend up to within 3 inches 
of the first floor level, the 
short vertical section of 2 
feet 11 inches being built 
at the same time as the 
footing proper in order that 
the first floor can be laid 
entire and the first story 
columns started above it. 

These short vertical 
lengths are reinforced with 
six 1-inch rods which ex¬ 
tend 4 inches down into 
the main part of the foot¬ 
ing and project 7 inches 
above the concrete so as to 
pass through the floor and 
connect with the column 
above. These vertical rods 
rest upon steel plates 3 
inches square, which dis¬ 
tribute the compression 
from the steel to the con¬ 
crete. Four l/4-inch hori¬ 
zontal hoops are placed 
around the vertical rods. The columns above 
the first floor are of slightly smaller dimensions, 
as shown by the offsets in Fig. 28. Thus, 
the portion below the first floor is 21 by 27 
inches, which reduces to 18 by 24 inches with 
a further reduction above the crane brackets. 
The reinforcement in the columns in the first 
story is the same as below the floor, six 1-inch 
rods butting upon the ends of the rods below 
and connected with them by a short pipe sleeve. 
One-quarter-inch hoops were spaced double, 
every 12 inches. 

The wall columns have footings similar to 
those of the interior columns, except of smaller 
dimensions and lighter reinforcement. The base 
is 7 feet 4 inches, reinforced with sixteen 14 -inch 
rods in each layer. Below the first floor the col¬ 
umn is 20 inches by 26 inches, reinforced simply 
with a 34 -inch rod in each corner and four 14 -inch 
horizontal hoops. 

Above the first floor the exterior columns are 
of T-shaped cross-section, as described in the 
paragraphs which follow, the column proper be¬ 
ing 14 by 22 inches in the first story and 12 by 
14 inches in the second story. 

CRANE BRACKETS. 

The brackets, shown in Fig. 28, which support 
ihe cranes, are of particular interest. To pro¬ 


vide for the shear, it was considered advisable 
to loop the reinforcing rods into the bracket, run¬ 
ning them out horizontally and then bending 
them down on an incline back into the column. 
The steel I-beams supporting the track for the 
crane rest directly upon these brackets and run 
the full length of the building. 

FLOOR SYSTEM. 

The floor of the first story was laid directly 
upon the ground after filling in around the col¬ 
umns and thoroughly puddling the earth. This 
floor is of 1:2:4 concrete with sleepers upon it 
and a 2 -inch oak floor. 

The second floor is supported in the two bays 
by. girders about 40 feet long in the clear, 12 
inches wide and 5414 inches deep from top of 
slab. In the bottom of the girder, to take the 
tension, are ten 1-inch square twisted rods and, 
to provide for the negative bending moment, 
five 1-inch rods were placed at the top of the 
beams over the supports. The shear or diag¬ 
onal tension is provided for by these bent-up 
rods, together with sixteen 14 -inch and ten 14 - 
inch U bars. The reinforcement was rigidly lo¬ 
cated before the concrete was poured, so that it 
could not be displaced. 

In the central bay the net span is about 20 
feet and the girders are smaller, being 6 by 31 


47 








































Fig. 30—Bullock Electric Company Machine Shop in Operation. 


inches. The thickness of the slab is included in 
the depth of the girders in both cases, since the 
concrete for the girders and slabs was poured 
at one operation. 

The girders extend across the building from 
column to column, and are thus 16 feet apart 
on centers, giving a net span for the concrete 
floor slab of 15 feet in the outside bays and 15 
feet 6 inches in the middle bay. The slabs, 
which are designed by a load of 225 pounds per 
:square foot, are 7% inches thick, reinforced 
“with i/ 2 -inch bars spaced 6 inches on centers. In 
addition 1,4-inch rods about 2 feet apart run 
^across the building parallel to the girders to 
prevent contraction cracks. 

The wearing surface of the floor is %-inch 
maple flooring upon 3 by 4-inch sleepers spaced 
16 feet apart on centers and filled between with 
•cinder concrete. 

WALLS. 

The window area comprises a large percent¬ 
age of the wall surface, the openings in the con¬ 
crete being 12 feet 2 inches wide and in the lower 
story 23 feet 8 inches. The walls, 4 inches in 


thickness, were carried up at the same time as 
the columns, thus forming with them T-sections. 
Below and above the windows, the wall was also 
4 inches thick, with water table and sills. 

Each vertical section of wall was reinforced 
with two 1 / 2 -inch square bars in the first story 
and two 1,4-inch bars in the second story. Hori¬ 
zontal loops of i/4-inch wire were also placed 
about 2. feet apart. Above the windows the 
walls were reinforced with three horizontal rods 
and with vertical rods spaced about 3 feet apart. 

In order that the exterior of the new building 
should harmonize with the older shops in the 
same plant, the walls were surfaced with a sin¬ 
gle thickness of light-colored pressed brick. 
These were tied to the wall by the wires which 
were used in keeping the forms together. 
These ties were No. 8 galvanized iron wire about 
12 inches long, which projected from the con¬ 
crete about 6 inches. They were spaced every 
18 inches horizontally and every six courses of 
brick vertically. The projecting ends were 
turned in a hook by the brick-layer and bedded 
in the mortar joints just like regular brick an¬ 
chors. 


48 




















Fig. 31—Factory of Hunter Illuminated Car Sign Company. 

FACTORY OF HUNTER ILLUMINATED CAR SIGN COMPANY 


The factory building of the Hunter Illuminated 
Car Sign Company, at Flushing, L. I., is built 
with walls of hollow tile. 

The hollow tile used in the construction are 
called “Tilecrete” and are manufactured under 
the “Pauly Process.” By this process the con¬ 
crete, composed of Portland cement and 
carefully selected aggregates and mixed to the 
consistency of grout, is poured into molds sur¬ 
rounded by a steam jacket. Enough water is 
evaporated from the concrete by the heat to per¬ 
mit the withdrawal of the tile within a few min¬ 
utes, although enough water is left to thoroughly 
harden the tile. The finished product has the 
density and uniformity of wet mixed concrete 
and is very true and uniform in shape and size. 

While the tile itself is remarkably cheap, it is 
in erection that the greatest economies are ob¬ 
tained, as the large size of the tile enables a given 
volume of wall to be erected with fewer units 
than with any other materials. Experience has 
demonstrated that a mason can easily lay 400 
10-inch tiles per day, thus erecting eight times 


as much wall as would be possible with brick. 

DESIGN. 

The building is 80 feet long and 75 feet wide, 
two stories in height with a one-story office addi¬ 
tion 21 by 31 feet. The side walls of the main 
building are 22 feet high and the gable walls 31 
feet high. 

The floors are of wood, the first floor being 
supported on Lally columns and the roof on 
wooden posts. The sills and lintels are all of 
reinforced concrete built in place. 

The partial plan and sections in Fig. 32 show 
the details of design. 

CONSTRUCTION. 

After the footings were put in the foundation 
walls were built up of concrete hollow tile 12 by 
16 by 12 inches, pointed and filled with concrete, 
so as to form a 16-inch solid wall without the use 
of wooden forms. The main walls were then car¬ 
ried up in 8-inch hollow tile broken out in pilas- 


49 












p/esrrtooe plan w 

Fig. 32—Partial Plan and Cross Section of Hunter Factory. 


ters on the side walls 15 feet on centers and on 
the gable walls 18 feet 6 inches on centers. 

The pilasters thus are 16 inches by 32 inches 
and in order to form columns were filled solid 
with concrete and reinforced with %-inch steel 
rods. 

After the building was completed the tile were 
carefully pointed on both sides of the wall and 


the faces cleaned down, so that at a short dis¬ 
tance away the work has the appearance of di¬ 
mension stone. 

COST. 

The building cost complete, including heating 
and plumbing, about $10,000 or approximately 
75 cents per square foot of floor space. 


50 








































































Fig. 33—Wholesale Merchants’ Warehouse, Nashville. 

WHOLESALE MERCHANTS’ WAREHOUSE 


The immense reinforced concrete warehouse 
at Nashville, Tenn., illustrated above, is the re¬ 
sult of a scheme of co-operation of a number of 
the most prominent merchants of that city. They 
previously had conducted their business in vari¬ 
ous individual warehouses in the business section 
of the city and some distance from the railroad. 
To better their condition the idea was conceived 
of forming the Wholesale Merchants’ Warehouse 
Company to erect a fireproof building alongside 
of the tracks, and thus save the large expense of 
hauling and at the same time obtain greatly re¬ 
duced insurance rates. 

Insurance on the stock carried by the mer¬ 
chants in the old type of frame buildings ranged 
from $1.80 to $2.20 per hundred, while in the 
new fireproof, reinforced concrete structure the 
rates were reduced to $0.40 per hundred. 

LAYOUT. 

The general plan is a framing of longitudinal 
beams with no girders and the division of the 
floors into compartments for the different firms. 


The interior columns are spaced 12 feet apart in 
one direction and 16 feet 7i/ 2 inches in the other. 
In general, the beams rUn lengthwise of the 
building from column to column, with no sup¬ 
porting girders, while cross-beams are placed at 
intervals to tie the building together and to sup¬ 
port the partitions. 

These cross-beams and their partitions are 
not spaced uniformly, but at different distances 
apart, so as to afford a pierchant a choice of 
several sizes of rooms, each of which extends the 
full depth of the building. For example, the spac¬ 
ing of the partitions is three bays in a large num¬ 
ber of cases, while in one portion of the building 
the spacing is one and a half bays; in another, 
two bays; and in still another four bays. The 
widths of the compartments thus vary from 
about 24 feet to 66 feet, with a uniform depth of 
about 130 feet. 

The beam design is somewhat different than 
usual along the front and rear of the building. 
Here the cross span is 18 feet instead of 12 feet, 
and short cross girders are introduced, each of 
which supports a floor beam at its center. The 


51 















Fig. 34—Interior of Wholesale Merchants’ Warehouse. 



projecting girders at the rear of the building, 
that is, at the top of the plan in the figure, sup¬ 
port the roof over the loading platform in the 
basement. 

In order to take advantage of the full width of 
the lot, and yet not encroach upon the loading 
platform with the basement columns, the rear 
wall of the building from the first floor up to the 
roof is supported by the ends of the floor girders 
which project at each story about 30 inches, thus 
acting as cantilevers. 

Because of the variety in the weights of the 
goods to be stored, the floors were designed for 
different loadings. The first floor was calculated 
for 350 pounds loading per square foot of sur¬ 
face, the second floor for 300 pounds and the 
third and fourth floors for 250 pounds. The roof 
was figured for a snow load of 40 pounds per 
square foot. These figures in each case repre¬ 
sent live loads, and do not include the weight of 
the concrete itself. 

BEAMS AND SLABS. 

Details of the construction of a typical beam 
and slab are drawn in Fig. 35 (p. 53). These are 


designed for the first story to support a floor load 
of 350 pounds per square foot in addition to the 
weight of the reinforced concrete itself. 

Inspection of the plans shows that three of the 
six bars in the beam are bent up on an incline 
and run across over the supports, lapping there 
a distance of one-quarter of the span length. 
Several % 6 -inch round stirrups are also provided 
to assist in taking the shear. The dimensions 
of the beams, 12 by 20 inches for the longitudinal 
beams of which the details are shown, and 10 by 
16 inches for the cross-beams supporting the par¬ 
titions, are given in the customary way, measur¬ 
ing the depth from the top of the slab to the 
bottom of the beam, and assuming, of course, 
that the standard practice is followed of placing 
the concrete in the beams and slabs at one time, 
so as to form a monolithic T-section. The rods 
in the bottom of the beam are placed in two lay¬ 
ers, so as to bring them far enough apart to pre¬ 
vent the concrete splitting between them. 

It will be noticed in the floor sketches that 
1 / 2 -inch bars 5 inches apart, to form the rein¬ 
forcement for the slab, are placed in the bottom 
of the slab at the center of its span, but that all 


52 












run up toward the supporting beam, and thus in 
the longitudinal section of the beam at the top 
of the diagram, these rods which are shown by 
so many dots, are close to the upper surface. 
This plan is somewhat easier to follow than 
where rods are alternately horizontal and bent 
up, and it is preferable to the latter because the 
negative bending moment at the ends of a con¬ 
tinuous slab is at least as great as the positive 
moment in the center, so that fully as much rein¬ 
forcement is required to take the pull at the top 
Gf the slab over the supports as is necessary in 
the bottom at the middle of the span. 

The roof is of concrete 
of lighter design, and the 
slab, which is 3 inches 
thick, is laid on a slope of 
*4 inch per foot and is cov¬ 
ered with tar and gravel 
roofing. 


COAL TRESTLE. 

Comparatively few designs of reinforced con¬ 
crete coal trestles have been published, and the 
trestle erected in connection with this building 
is therefore shown in considerable detail. Its 
elevation is given in Fig. 33 (p. 51), and the 
details in Fig. 36. 

COST. 

The entire cost of the building was about $357,- 
000, including finish, of which $192,000 was for 
the reinforced concrete and the excavation. The 
cost of the construction plant, which is included, 
was $19,000, an unusually large amount. 


COLUMNS. 

Although the floor 
loads are heavy, the col¬ 
umns are only 19 inches 
square in the basement 
and less than this in the 
stories above because 
the spacing between them 
is comparatively small. 
The general type of re¬ 
inforcement is four y 8 - 
inch vertical bars near 
the corners with 3/16- 
inch horizontal loops at 
intervals of 5 to 12 inches, 
varying with the dimen¬ 
sions of the columns. In 
the first story %-inch 
vertical bars were used 
with loops 4 inches apart. 

The columns are de¬ 
signed for a loading of 750 
pounds per square inch, 
a seemingly high stress 
for the proportions of ce¬ 
ment to aggregate used, 
1:2*4:4i/2> but * n making 
the calculations no ac¬ 
count is taken of the area 
of concrete outside of the 
steel loops nor of the 
strength of the vertical 
steel, so that the loading 
is really conservative. 


_ 


zCordary 

Trussed] 


SpcTtQMJZ: tAcal BcamIm 



'tfear r ^-S^'J/ad f~~1 rt'Carda/y-SVarrC f~1 ( ycordary-E4'd7r?arA? [~~l 

. ij= 


1—I found Eoc/s 


'■\6-mrfrv gH 

Cj?Q 53 $/zCTion OF Tyhcal dn/iM and .Slab 


[dem/0'xJ6‘ 

-jd-j'Ccr dary 


Fig 35—Details of Reinforcement of Typical Beam and Slab. (See p. 52.) 


'-/EC*/8'Concrete Cap or? rCefa/n/na M?//-£eMorceme/?d4-CCordary. 

J/a/M //a/M //a/ m //a/M ,,rr /M na/m 



Co/umns A - /d'x/d' jrdd 
4-§'nx/nd rcdi. 
Co/umna d -9‘x9'*'?M 
4--k'round nodi 


Fig. 36—Details of Coal Trestle. 
53 






















































































































































Fig. 38—Plant of Boston Woven Hose and Rubber Company. The plant was designed by Mr. John O. DeWolf, Archi¬ 
tect and Engineer, of Boston, Mass., with Mr. Edward A. Tucker, Boston, Mass., as Concrete Engineer, and Mr banford 
E. Thompson, Boston, Mass., as Consulting Engineer, the Contractor being Benjamin Fox, of Boston, Mass. 


PLANT OF BOSTON WOVEN HOSE AND RUBBER COMPANY 


The plant of the Boston Woven Hose & Rub¬ 
ber Company, located in Cambridge, Mass., in¬ 
cludes a hose manufacturing building and two 
warehouses of reinforced concrete covering ap¬ 
proximately 220,000 square feet of floor space. 

An interesting feature in connection with these 
buildings is the speed with which they were 
erected, the work being started on July 19 and 
completed ready for occupancy by the middle of 
October, only thirteen weeks being required. 
Such a record would have been absolutely impos¬ 
sible with any other type of construction than 
reinforced concrete. 

DESIGN. 

The hose building is 322 feet long by 60 feet 
wide, with four stories each 15 feet high from 
top of floor to top of floor. A single row of col¬ 
umns spaced 10 feet 4 inches on centers runs 
through the center of the building. The floor 
system is made up of reinforced concrete girders 
spanning across the building 30 feet from the 


interior columns to wall pilasters and carrying a 
5-inch floor slab. 

The photograph in Fig. 39 (p. 55) shows the 
interior of this building. 

The floors were designed for a live load of 150 
pounds per square foot. 

The girders are 18 inches wide and 28 inches 
deep and are reinforced with seven 1-inch bars, 
five of these being bent up and three being car¬ 
ried horizontally over the supports into the adja¬ 
cent bay. The floor slab is reinforced with 
i/ 2 -mch bars, 7 inches on centers, with two out of 
every three bars bent up and staggered so that 
exactly as much steel is carried in the top of the 
slab over the supports as in the bottom of the 
slab in the middle of the span. 

The method of arranging the ducts for the 
blower system of heating is of special interest, 
these ducts being carried up inside the wall pilas¬ 
ters, so as to do away with all unsightly or cum¬ 
bersome heating equipment. 


54 




























In order to provide for the 
excess compression in the con¬ 
crete at the bottom of the 
girder at the support, the 
girders were made deeper next 
to the columns by forming a 
flat haunch. 

The concrete for the floor 
construction was mixed in the 
proportions of 1 part Atlas 
Portland Cement to 2^4 parts 
sand to 5 parts broken stone 
of size to pass a %-inch ring, 
while for the columns and pi¬ 
lasters a mixture of 1 :3 

was used. 

The stresses assumed in 
computing the sizes of the 
various members were 500 


Fig. 39—Interior View of Hose Building. 


Fig. 40-—Hoisting Concrete Pile Into Driving Position. 


In the warehouses the second and fourth floors 
are designed for a live load of 200 pounds per 
square foot, and the third floor for a live load of 
.300 pounds per square foot. For these loadings 
it was found more economical to use two rows of 
columns instead of a single row—otherwise the 
construction is substantially the same as in the 
hose building. 

Fig. 41 is a cross section of one of the ware¬ 
houses and shows the details of design and con¬ 
struction for the floor system, columns, walls and 
footings. 


pounds per square inch ex¬ 
treme fiber stress in the mem¬ 
bers of the floor system, and 
600 pounds per square inch 
direct compression in the con¬ 
crete, this stress being per¬ 
missible because of the rich 
proportions used, and 16,000 
pounds per square inch ten¬ 
sion in the steel. Corrugated 
bars were used throughout 
the buildings. 

All floors were finished with 
a 1-inch granolithic surface 
mixed in the proportions of 1 
part cement to 2 parts sand 
and placed within three hours 
after the under slab, so as to 
form one homogeneous slab. 

The roof surfaces were cov¬ 
ered with three-ply tar and 
gravel roofing laid directly on 
the concrete, the roof pitch be¬ 
ing 1/2 inch to a foot. 

REINFORCED CONCRETE PILES. 

The power house is carried on reinforced con¬ 
crete piles, which were formed in horizontal 
molds above ground and then driven. Fig. 102 
(p. 90) gives the design of a typical pile and 
the photograph in Fig. 40 shows one of the piles 
being lifted into position for driving. 

The piles taper from 14 inches at the top to 
9 inches at the point and are reinforced with 
four %-inch bars connected at intervals, as 
shown, with 14 -inch warping bars. The concrete 


55 





















was mixed by hand in pro¬ 
portions 1:2:4, using %- 
inch trap rock. A 1 1 / 2 -inch 
galvanized iron pipe was. 
cast in the center of the 
pile for a water jet. 

The piles average about 
30 feet long and were 
driven at the age of thirty 
to forty days. The hammer 
weighed 4,700 pounds and 
the blows were cushioned 
by a head consisting of a 
plate iron collar 16 inches 
square on the inside and 3 
feet in height, encasing an 
oak block 16 by 16 by 18 
inches to the bottom of 
which six thicknesses of 
rope and four layers of rub¬ 
ber belting were nailed. The 
usual drop was 3 feet, but 
in some cases this was in¬ 
creased to 10 feet without 
injuring the pile. 

The average cost of the 
piles driven was $1.63 per 
linear foot of pile. 

CONSTRUCTION. 

The construction plant 
consisted of a li/ 2 -yurd 
Ransome mixer with a Ran- 
some hoist in a tower. The 
concrete was conveyed in 
Ransome carts and barrows. 
All forms were made on the 
ground and hoisted into 
place by a derrick, which 
also lifted the steel rein¬ 
forcement from the ground 
to its destination. The 
forms were used over four 
times on each building. 

The total cost of build¬ 
ings was about $270,000. 




56 


Ju/p/wg jo ? 
























































































Fig. 42—Bush Model Factory No. 2. The builder of this concrete factory was the Turner Construction Company. 
Mr. E. P. Goodrich, formerly chief engineer for the Bush Terminal Company, prepared the structural design and 

Mr. William Higginson was the architect. 


BUSH MODEL FACTORY No. 2 


The plant of the Bush Terminal Company, lo¬ 
cated in South Brooklyn on the east shore of 
New York Bay on Thirty-sixth Street, between 
Second and Third Avenues, will cover when com¬ 
pleted an immense area and comprise some hun¬ 
dred and fifty warehouses and factories. Many 
of the more recent of these buildings are of re¬ 
inforced concrete construction, the factory se¬ 
lected from this group for description being 75 
ft. wide by 599 ft. long, and six stories high 
above the basement. Several features of the de¬ 
sign are of unusual types. 

The Terminal Company owns some 160 acres 
of land with nearly three-quarters of a mile of 
water front. A number of piers, each one-quar¬ 
ter of a mile in length, with wide docks between, 
permit the largest ocean steamers to discharge 
and load without interference. The large ware¬ 
houses, 50 by 150 feet, and from four to seven 
stories high, provide the steamship lines renting 
these Bush piers with unusual facilities for both 


the storage and the trans-shipment of freight. 

In addition to this storage and shipping busi¬ 
ness handled by the piers and warehouses, a 
plan is already being carried out to erect eighteen 
fireproof factories or loft buildings, their floor 
space to be rented for manufacturing purposes. 
The first of these factories, built in 1905, and 
the second, called the Bush Model Factory No. 
2, built in 1906, offer unusually attractive fea¬ 
tures because of the excellent facilities afforded. 
The details of the latter, which is shown com¬ 
plete in Fig. 42, form the subject of this chap¬ 
ter. 

DESIGN. 

Instead of the usual system of beams, girders 
and slabs, the floors consist essentially of heavy 
girders directly supporting ribbed slabs, de¬ 
signed eo that the under surface presents a cor¬ 
rugated or ribbed appearance, the purpose being 
jto use for the necessarily long spans a minimum 


57 












quantity of concrete placed most effectively to 
take the loads upon it. 

An idea of the general plan of the structure 
is gained from Fig. 43. In order to present it 
on a fairly large scale, only one end of the build¬ 
ing, a length of about 225 feet in a total of 599 
feet, is shown. 

The sectional elevation may be seen in Fig. 
44. 

Two lines of columns 16 ft. 7 in. on centers 
divide the factory into aisles about 24 ft. in 
width, thus giving exceptionally good floor space 
for either storage or manufacturing. Heavy 
girders run lengthwise of the building from col¬ 
umn to column, while spanning the distance be¬ 
tween these two lines or girders and the walls 
is the ribbed floor system. 

Two groups of four elevators each are located 
one-quarter way from each end of the building, 
and in adjoining bays on each side of both 
groups of elevators are the stair wells. The first 
floor plan, Fig. 43, shows the stairs to the base¬ 
ment only on one side of the elevators, but an 
additional flight is provided for the stories 
above. Except for the location of the stairs, 


the floor system of the different stories is identi¬ 
cal, thus simplifying the design and permitting 
the use of the same forms throughout. 

The roof is surrounded by a fire wall 3 feet 6 
inches high. A series of skylights over the cen¬ 
ter aisle afford additional light to the top story. 

Round rods formed into trusses on the ground 
and raised to place ready to drop into the forms 
provide the reinforcement. The proportions of 
the concrete used throughout were one part 
Portland cement, 2 parts sand, 4 parts stone, be¬ 
ing equivalent in actual volume to one barrel 
(4 bags) cement, 7.2 cubic feet of sand, and 14.4 
cubic feet of broken stone. The aggregate con¬ 
sisted of sand excavated by dredges from Cowe 
Bay, and washed gravel of a size passing a 94- 
inch sieve. 

COLUMNS. 

The column footings are supported by wooden 
piles, and the area of the footing is so large in 
proportion to the size of the columns as to re¬ 
quire a special design of heavy horizontal rods 
and vertical stirrups. 

In Factory No. 1 the interior columns are cyl- 


58 































































































































































































































































Fig. 44 —Sectional Elevation of Bush Factory No. 2. 


indrical and com¬ 
posed of an outside 
shell of cinder con¬ 
crete 214 inches 
thick. These cinder 
concrete cylinders 
were prepared in 
advance in 2-foot 
lengths in a zinc 
mold, with spiral 
hooping and ex¬ 
panded metal form¬ 
ing the inner sur¬ 
face. After hard¬ 
ening, they were 
set one upon an¬ 
other in the build¬ 
ing, and filled with 
concrete. 

In Factory No. 2 
the columns are oc¬ 
tagonal in shape, 
and composed whol¬ 
ly of gravel con¬ 
crete. Just below 
the girders the sec¬ 
tion was made 
square (see Fig. 46, 
p. 61), these square 
caps being the same 
size on all the 
stories so as to 
avoid altering the 
rib and girder 
molds. 

The columns 
were spirally reinforced with round high car¬ 
bon steel % to inch in diameter, the pitch 
varying in the different stories. The loading 
upon the columns was graduated from 500 
pounds per square inch of their section for the 
upper floor to 1,000 pounds per square inch in 
the basement. This, however, assumed full 
loads on all the floors at the same time, which 
would not ordinarily occur, so that the columns 
in the lower stories are liable to be stressed 
much less than the nominal figures. The spiral 
hooping is computed to assist in bearing the 
load. 

FLOOR SYSTEM. 

The general scheme of design has been re¬ 
ferred to in paragraphs above. Longitudinal 
girders of 13 feet 4 inches net span, supported 
by columns 16 feet 7 inches on centers, carry 


the ribbed slabs which run across the building 
with a net span of about 23 feet. 

The details of design of the beams and ribbed 
slabs are drawn in Fig. 45. The ribs are V- 
shaped in cross-section, as shown in Sections aa 
and bb. Two 1-inch round rods, one bent up at 
the points determined by moment diagram, and 
the other extending horizontally to the girders, 
provide for the tension and 1 / 2 -inch stirrups are 
bent around and wired on to the horizontal rods. 
Ribs A, which are shown in the diagram, con¬ 
nect the two girders, while ribs B, which run 
from the girders to each wall, are similar in 
design, except that the upper rod cannot project 
beyond the support, and is therefore anchored 
by bending it with a quarter turn around an¬ 
other rod which runs at right angles to it in the 
wall. 

The steel is designed for a maximum pull of 


59 























































































































16,000 pounds per square inch when the full al¬ 
lowed load is on the floor, and stirrups are pro¬ 
vided wherever the shear exceeds 50 pounds per 
square inch. The floors are designed for a load¬ 
ing of 200 pounds per square foot besides the 
dead weight of the concrete. 

The design of the principal girders is also 
shown in Fig. 45. The stirrups are close to¬ 
gether at the ends of the girders where the 
shear is the greatest and each stirrup is looped 
around the tension rods, then passes up on each 
side of the girder and across, as shown in the 
sections. The stirrups are ^-inch in diameter 
near the end of the beam, then at the points 
where the large rods are inclined and thus take 
a portion of the shear, the size is reduced to 
. 5 /i 6 inch, and this is continued to the center of 

the beam, the spacing gradually becoming wider 
as the shear decreases. The tensional reinforce¬ 
ment in the girders consists of four 114 -inch 
rodsytwo of which aye bent up just beyond the 
one-quarter points, arid extend nearly to the cen¬ 
ter of the column, where each is connected with 
the reinforcement in the next girder by an oval 


link of 15/16-inch round steel (see figure above). 

In the bays around the elevators, the rib 
forms were dropped 8 V 2 inches, so as to make 
the slabs between the ribs 12 inches thick, as 
shown in Section CC, Fig. 43. 

No reinforcement was placed longitudinally 
of the building at right angles to the ribs. In 
the floors first laid with the V-shaped rib, slight 
shrinkage cracks occurred between the ribs and 
parallel to them. These, however, did not open 
or indicate any structural weakness, and they 
were eliminated by more thorough rodding of 
the surface. 

The underside of the floor construction, and 
also the columns, are shown in the photograph, 
Fig. 46 (p. 61). 

CONSTRUCTION. 

Two mixing plants were located in the base¬ 
ment of the building near the two elevator 
shafts. The arrangement of the entire plant 
was according to the Ransome design. Each 
mixer was located on a platform about 3 feet 
above the floor level, and the raw material sup- 


60 
























































































































































-View of Interior of Bush Model Factory No. 2 



plied to it by wheelbarrows. 

The building was completed in seventy-four 
working days, the average progress being 10.4 
days per story. During this time 16,000 cubic 
yards of concrete were placed and 950 tons of 
steel. The usual gang consisted of 80 carpen¬ 
ters and 180 laborers. 

The photograph shown in 
Fig. 47, shows the general 
layout of the forms, the 
girder forms extending 
lengthwise of the view with 
the ribs at right angles to 
them. The rib forms, which 
are approximately triangular, 
rest directly upon the sides 
of the girder molds, and nar¬ 
row pieces of plank are 
dropped between them to 
form the bottom of the rib. 

The total cost of the build¬ 
ing complete was approxi¬ 
mately $450,000. It has au¬ 
tomatic sprinklers, steam 


heat, ample toilet rooms, heavy freight eleva¬ 
tors, wire glass windows in metal frames, stand¬ 
ard automatic fire doors, hardwood floors, and 
so forth, to make a really model factory. 

Since the completion of this factory, numerous 
other model buildings of concrete have been built 
for this same concern. 


Fig. 47—View Illustrating Form Construction for Bush Terminal Factory. 
See Fig. 42 for Finish View. 


61 



























Fig. 48—Packard Motor Car Factory. 


PACKARD MOTOR CAR FACTORY 


The Packard Motor Car Company at Detroit, 
Michigan, turned out 700 automobiles in 1905. 
The demand for these cars necessitated an en¬ 
largement of the plant, and in the spring of 
1906, after careful consideration of the various 
types of construction, it was decided to build 
the new factory of reinforced concrete. The 
building illustrated in Fig. 48 is the result. 

Plans were drawn at once by Mr. Albert 
Kahn, architect, and the contract was let to the 
Concrete Steel and Tile Construction Company, 
of Detroit, the Trussed Concrete Steel Company 
acting as engineers. 

The structure, as is shown on the plans, is 
long and narrow, and in the form of an L, so 
that all parts of the floor are well lighted. It is 
proposed at some future time to extend the 
building by carrying out another wing. At pres¬ 
ent there are two stories, and the roof is de¬ 
signed as a floor with a temporary covering, as 
described below, so that another story can be 
added at a later date. The first floor is laid 


right on the ground—there is no basement. 

The building is designed to provide very large 
floor area without interference of columns. A 
single row of columns runs through the center 
of the factory, and these are 32 feet apart on 
centers, a distance slightly greater than the 
space between the line of columns and the walls 
on each side. 

Although a motor car appears to be a heavy 
machine in itself, the parts are comparatively 
light, and by placing the heavier machinery on 
the ground floor, it was possible to allow a floor 
load of only 100 pounds per square foot, in addi¬ 
tion to the dead load or weight of the structure 
itself. In certain parts of the floor, this load 
is increased, around the elevators especial care 
being taken to give an excess of strength. This 
comparatively light live load together with the 
type of floor construction selected, a combina¬ 
tion of tile and concrete, permitted the rather 
unusually long spans. 

The general plan, Fig. 49, shows the layout 


62 














Z3Z2.' 



5tcono rLOQ/c plah 

Fig. 49—Floor Plan and Beam Details in Packard Factory 


on the floor, with an outline of the location of 
the beams, girders and columns. 

FLOOR SYSTEM. 

The first floor is built directly upon the 
ground. The top soil was removed and the sur¬ 
face thoroughly tamped, then covered with 6 
inches of cinders rammed hard to receive the 
concrete. On top of this porous layer, a 5-inch 
thickness of concrete in proportions 1 part ce¬ 
ment and 2 parts sand to 5 parts broken lime¬ 
stone was spread, and covered with a 1-inch 
mortar surface, laid before the concrete below 
had set, in proportions 2 parts cement to 3 parts 
sand, and thoroughly troweled with a steel 
trowel to a smooth surface. This was divided 
into sections as it was being laid to provide 
contraction joints. 

In the floor above, the wide spacing of the 
columns, already mentioned, necessitated beams 
and girders of unusual length, and consequently 
of unusual width and depth. The girders (see 
Fig. 49) are 30 feet 8 inches in net length be¬ 
tween columns, or 32 feet 8 inches on centers, 
and measures 22 inches wide by 36 inches deep 
from top to slab. Each girder supports one 
beam at the center of its span, the alternate 
beams running directly into the columns. The 
reinforcement, which consists of Kahn trussed 
bars,* is very clearly seen in section NN in the 

*See Illustration, Fig. 49. 


figure. The girder selected, as shown on the 
plan below it, is taken at the intersection of the 
two wings of the building, and the column at 
the right is therefore narrower than the left- 
hand support, the latter illustrating the typical 
columns in the building. 

The floor system, as already mentioned, is de¬ 
signed for a load of 100 pounds per square foot 
in addition to the weight of the concrete and 
steel. The design is figured so that this loading 
will not produce a tension in the steel exceeding 
16,000 pounds per square inch, and will keep the 
compression in the concrete everywhere within 
the limit of 500 pounds per square inch.* The 
proportions of the concrete are one part Atlas 
Portland cement, 2 parts sand, 4 parts broken 
limestone, the exact measurements being one 
barrel (4 bags) cement to 7.56 cubic feet sand 
to 15.10 cubic feet stone. 

The shear or diagonal tension is provide^ for 
by bending some of the tension rods and also by 
the bent-up portion of the individual bars. 

The beams, of which a typical section, MM, is 
also shown in Fig. 49, are 27 feet 1 inch net 
span between girder and wall column. The gen¬ 
eral construction is similar to the girder shown 
above it and labeled beam “B” except that fewer 
bars are bent up because the shear is less. The 

♦Figured by the parabolic formula, or nearly 600 pounds by 
the straight-line formula. 


63 

















































































































section of the typical beams is 30 inches deep 
and 18 inches in width. 

A somewhat peculiar slab section is shown in 
the upper portion of section MM. This is made 
up of sections of tile and concrete placed alter¬ 
nately. The floor slab is 14 feet 6 inches net 
span between beams, and consists essentially of 
a series of concrete beams 8 inches deep by 4 
inches in width spaced 16 inches apart on cen¬ 
ters and reinforced with Kahn trussed bars. 
These little beams run directly into the upper 
surface of the regular beams, labeled “A” on 
the plan, and are supported by them. 

Between these little beams hollow tile is laid, 
the method of construction being to first place 
the tile upon the level panel form, then set the 
reinforcing metal in position between the rows 
of tile, and pour the concrete. The object of the 
insertion of tile is to lighten the floor slab, and 
thus reduce the weight upon the beams and 
girders by occupying space which must other¬ 
wise be solid concrete. It also permits very sim¬ 
ple form construction, consisting chiefly of a 
large surface readily built and removed. 

After hardening, the under surfaces of the 
floors are plastered with 2 inches of Portland 
cement mortar to hide the tile and form the ceil¬ 
ing. On top of the floor slab, a 2-inch wearing 
surface of cement mortar finish is also laid to 
make the finished floor. 


The beams around the elevators are specially 
constructed to sustain a weight of 8,000 pounds 
live or superimposed load, plus 8,000 pounds 
from the counterweights, plus 4,000 pounds, 
the weight of the elevators loaded. 

The original specifications called for a roofing 
designed to carry 40 pounds per square foot, but 
it was afterward decided to build this as a floor 
of the same construction as the second floor so 
that another story could be added when re¬ 
quired. On top of the level surface thus formed 
a layer of cinders was spread and shaped so as 
to pitch to stumps; a 1-inch layer of mortar was 
laid on the cinders, and upon this tar and gravel 
roofing. 

COLUMNS. 

The interior columns are in general 24 inches 
square and designed for a safe loading which 
produces a compressive stress in them not ex¬ 
ceeding 450 pounds per square inch. The con¬ 
crete was made in proportions one part Port¬ 
land cement to IV 2 parts sand and 2 parts stone, 
and reinforced with Kahn trussed bars. 

The wall columns are similar in design, but 
smaller in section and spaced 16 feet 4 inches 
apart on centers, so that all the cross beams run 
directly into them. A longitudinal beam at 
each floor line connects these wall columns and 
also supports the brickwork, which is built up 
to the level of the window sills. 


64 



Fig. 51—Concrete and Tile Floor Under Construction. 



Fig. 52—Interior View of Packard Factory Completed. 


65 


















































































Fig. 53—Interior View of Syracuse Cold Storage Company’s Warehouse. 



lip * t*** - *-* 


WAREHOUSE OF SYRACUSE COLD STORAGE COMPANY 


The warehouse of the Syracuse Cold Storage 
Company, Syracuse, N. Y., illustrates the appli¬ 
cation and the economy of factory-made unit- 
concrete floors. 

The warehouse is a six-story and basement 
building approximately 78 feet square. While 
it was originally designed for mill construction, 
alternate bids were taken using both a monolith 
concrete design and a structural steel frame in¬ 
cased in concrete with separately molded floor 
sections. This last type of construction was 
found to be cheaper than either of the others 
and consequently was adopted. 

The photograph in Fig. 53 is an interior view 
of the completed structure. 

i DESIGN. 

With'the exception of the top floor the building 
was designed to carry a live load of 300 pounds 
per square foot. The columns were spaced 15 
feet 3 inches on centers both ways. The struc¬ 
tural steel frame, which consisted of plate and 


angle columns carrying Bethlehem girder beams, 
was designed to carry the entire live and dead 
loads, the concrete encasing the columns and 
girders being considered only as fireproofing. 

The separately molded floor sections, details 
of which are shown in Fig. 54, rested on the 
lower flange of the I-beams, reinforcement be¬ 
ing provided for ties over the top flanges. The 
connections were filled with field concrete placed 
after the members were in position. 

CONSTRUCTION. 

The concrete floor sections were delivered both 
by rail and by team from the plant at which 
they were manufactured, three miles distant. 
The concrete members were unloaded by a boom 
attached to the steel columns. They were dis¬ 
tributed about the building and set in place, as 
shown in Fig. 55, by chain hoists on portable 
I-beam trolleys. 

The top flange of one beam in each panel was 
coped to allow the beams to enter, and they 


66 





Detailed Cost of Syracuse Cold Storage Company’s 

Warehouse 

Building 78 ft. x 78 ft., steel frame fireproofed, having basement, six storage 
floors and concrete roof. Floors designed for 375 lbs. per sq. ft. total load. Total 
area of floors, 40,432 sq. ft.; volume, 424,480 cu. ft. 


Classification of Work 


pR. 


O 


Concrete materials in floors: cement at 

$1.40 bbl., stone at $1.10 ton. 

Reinforcing steel in floors, f.o.b. shop. . 

Labor fabricating reinforcement. 

Labor making floor sections and roof.. 

Labor ereqting members. 

Hauling and freight on members from fac¬ 
tory (2i|niles). 

Power, erection tools and supplies. 

Fixed factory charges, including power, 
interest and depreciation. 


Total for floors in place, not including 
pointing or grouting. 


Quanti¬ 

ties 


373 yds. 
105,810 


Cost 


$1,156.30 

1,454.40 

317.43 

2,605.69 

1,650.10 

382.57 

217.40 

500.00 


Total 
' Cost 


$8,283.89 


Cost 

per 

Yd. 


$3.10 


Cost 

per 

Lb. 


014 

.003 


Cost 

per 

Sq. 

Ft. 


.028 

.036 

.008 

.064 

.040 

.008 

.005 

.012 


250 


Cost 

per 

Cu. 

Ft. 


.0195 


a o® 

§<§ 

PR o 


Structural steel erected. 

Materials for concreting floors and fire¬ 
proofing steel. 

Labor pointing and concreting floors and 

fireproofing steel. 

Lumber for forms used in fireproofing steel 
Freight, delivery and cartage on field ma¬ 
terials. 

Tools, power and supplies. 


250,000 


Total for frame and fireproofing. 


$7,050.00 

244.84 

1,149.00 

150.00 

50.00 

100.00 


028 


8,743.84 


216 


.0206 


Engineering and superintendence. 

Total for floors, frame and fireproofing. 


$798.53 


$17,826.26 


019 

44 


.001 

.041 


O 


Brick curtain walls, stairs, trim, felt and 
gravel roof, and all other work to com¬ 
plete superstructure. 


$6,904.76 


Total cost of superstructure. 


$24,731.02 


.016 

.057 


Fig. 56 


67 



















































































were slid into position on the 
lower flange, wedged up, 
pointed underneath, the pro¬ 
jecting reinforcement tied 
over the top flanges and the 
spaces between the ends and 
edges grouted in solid. 

After the separately molded 
members were in place they 
were covered with a 2-inch 
granolithic wearing surface. 

COST. 

The table in Fig. 56 gives 
the detailed cost of the ware¬ 
house. As shown by this 
table the separately molded 
floor sections cost 20 cents 
per square foot in place, the 
steel frame and fireproofing 
21i/2 cents per square foot 
and the cost of engineering 
and superintendence about 2 
cents per square foot. This 
gives a total of only 44 cents 
per square foot or 4 cents per 
cubic foot of volume for 
frame and floor. These costs, 
of course, as well as the oth¬ 
ers in this book, are on the 
basis of labor and material 
before the Great War. 




Fig. 55—Method of Handling Separately Moulded Floor Section. 











































Fig. 57—Blacksmith and Boiler Shop of The Atlas Portland Cement Co. at Northampton, Pa. 


BLACKSMITH AND BOILER SHOP OF THE ATLAS PORTLAND 

CEMENT COMPANY 


At the plant of The Atlas Portland Cement 
Company, in Northampton, Pa., concrete is used 
extensively in construction, not only in founda¬ 
tions and for the cement storehouses, but also 
for the floors and walls of the newer buildings. 

In 1906 a new blacksmith and boiler shop was 
built with a 10-ton crane extending from wall 
to wall and running upon reinforced concrete 
arched beams. The building was designed by 
the company’s engineer and built by day labor. 
It is shown complete in Fig. 57. 

DESIGN. 

The shop is 309 feet 9 inches long, 55 feet 6 
inches wide and 31 feet 2 inches high to the bot¬ 
tom of the roof trusses, this height being nec¬ 
essary for the traveling of the crane. 

The walls consist of piers 14 feet on centers, 
with wall panels and windows between them. 
These piers are made of heavy section (see Fig. 
59 ) to support the crane, and for this purpose 
they project into the building 23 inches as far 


up as the crane runway, and at the top are con¬ 
nected with arches which are laid at the same 
time and form a part of the wall. The arches 
are reinforced with five %-inch rods spaced 
5 inches apart. The crane run is shown in 
Fig. 59. An 8-inch by 10-inch yellow pine tim¬ 
ber is bolted directly to the concrete beam, 
and upon this rests the track. The walls 
between the piers, which are dovetailed into 
them, as shown, are 9 inches thick. This is 
somewhat excessive, but the extra quantity of 
concrete may be justified by the low cost of ma¬ 
terials and the lean proportions of the concrete, 
which are 1 part cement to 4 parts sand to 5 
parts gravel. There is no reinforcement in the 
wall panels except directly above the windows. 

A cross-section of the shop with its steel roof 
trusses is shown in Fig. 59. 

CONSTRUCTION. 

Somewhat unusual methods of construction 
were employed. The piers were first run up to the 


69 

















Fig. 58—East Wall of 
Blacksmith and Boiler 
Shop of the Atlas Port¬ 
land Cement Company 


Fig. 59—Cross Section of 
Blacksmith and Boiler 
Shop of the Atlas Port¬ 
land Cement Company 


70 




































































































































































































































Fig. 60—Wall Piers for The Atlas Portland Cement Company Building. 


Fig. 61—Panel Wall Forms for The Atlas Portland Cement Company Building. 


full height of the building, as 
illustrated in the photograph, 

Fig. 60. Then the panel 
forms were placed, as in Fig. 

61, and the concrete poured 
between them. 

The window frames had 
been set in advance, so that 
the openings were formed in 
each wall panel as it was 
poured. The only tie rods 
which were inserted to con¬ 
nect the piers and the wall 
panels were at the corners of 
the building, where i/ 2 -inch 
horizontal rods 2i/ 2 feet long 
were placed every 3 feet in 
height. 

Above the foundations of 
the shop, 792 cubic yards of 
concrete were required, with 
only 5,570 pounds of steel. In 
the foundation 460 cubic 
yards were laid in addition. 

The concrete was mixed by 
hand, and the usual gang con¬ 
sisted of 2 foremen, 17 men 
mixing, 4 men hoisting, 4 men 
placing, and 6 carpenters. The 
wages for the laborers ranged 
from $1.20 to $1.50 per day, 
with a $2 rate for the car¬ 
penters. The total cost of the 
concrete in the foundations 
and walls was $29,328, which 
is equivalent to only $4.93 per 
cubic yard of concrete, an ex¬ 
ceptionally low price. The 
cheapness of labor partially 
accounts for the low cost. Or¬ 
dinarily, in building construc¬ 
tion with thinner walls and 
higher material and labor costs, the unit price 
per cubic yard will be greatly in excess of this 
figure. 

The forms, of hemlock lumber, costing $25 
per thousand, were dressed only on the side next 
to the concrete. About 19,000 feet of lumber 


was used at a cost of $485, the labor on forms 
being about $5,500. Although the forms were 
used ten times, the Engineer estimates the 
salvage for another similar job to be about 
60 per cent, as the lumber was but slightly 
injured. 


71 















Fig. 62—Exterior of Manufacturing, Assembly and Body Buildings, Pierce-Arrow Motor Car Factory 


PIERCE-ARROW MOTOR CAR FACTORY 


When the Pierce-Arrow Motor Car Co. of 
Buffalo, N. Y., was confronted with the neces¬ 
sity of more extensive and complete manufac¬ 
turing facilities they decided to build a manu¬ 
facturing plant complete in every detail; a plant 
that by its perfect system of light, heat and ven¬ 
tilation, its safety and freedom from decay, and 
its fireproofness, would attract and hold the 
best and most desirable skilled workmen. 

After a careful study of the various types of 
construction, reinforced concrete was selected. 
The satisfaction this material has given the own¬ 
ers is shown by the fact that during the wonder¬ 
ful development of the past four years, when the 
plant was increased from its original size of 
325,000 square feet of floor space to its present 
area of 780,000 square feet, all the buildings 
have been constructed entirely of reinforced 
concrete. 

A block plan of the factory is shown in Fig. 
63 (p. 73). The entire plant is laid out with 
the idea of attaining the highest degree of fac¬ 
tory economy. With this in view the buildings 


were arranged so that the materials in process 
of manufacture are gradually conveyed toward 
the Assembly Building, thus eliminating all con¬ 
fusion and unnecessary handling. 

MANUFACTURING BUILDING. 

The Manufacturing Building is a one-story 
structure, 205 feet by 401 feet, covered over its 
entire area with a sawtooth roof. The extremely 
careful work and accurate inspection necessary 
in turning out the small pieces that go into the 
mechanism of an automobile require the great¬ 
est possible amount of light. The sawtooth sky¬ 
lights and the exceptionally large windows made 
possible through the use of reinforced concrete 
have solved this problem admirably. 

The photograph, Fig. 62, shows the exterior 
of the Manufacturing Building with the Assem¬ 
bly and Body Buildings beyond. 

ASSEMBLY BUILDING. 

The Assembly Building, 122 feet by 401 feet 
in dimensions, is the most interesting of the 


72 











STORAGE AND NICKEL- 
PLATING BUILDING. 


A different type of design 
is followed in the Storage and 
Nickel-Plating Buildings, 
where the mushroom or gird- 
erless-floor construction is 
used. Fig. 66 is an interior 
view of the second floor of the 
Storage Building, and illus¬ 
trates the value of the flat- 
slab construction in storage 
buildings, allowing as it does 
complete utilization of all the 
space from floor to ceiling, 
without interference from 
beams or girders. 

' GARAGE. 

The Garage is a one-story 
building, 55 feet wide and 139 
feet long, with a monitor run¬ 
ning its entire length. Fig. 
68 shows the interior. In or- 


plant from a structural standpoint. Fig. 65 (p. 
74) shows the interior. Two three-ton cranes 
travel the entire length of the building, and in 
order to give these a large area of action, the 
building is divided by a single row of columns 
down the center. This necessitated roof girders 
spanning 61 feet and measuring 16 inches wide 
by 93 inches deep. These were reinforced with 
Kahn bars having a sectional area of 18 square 
inches. The crane girders, that is, the beams 
upon which the crane runs, span 25 feet from 
column to column and are of reinforced con¬ 
crete, the rails for the traveller being fastened 


Fig. 63—Block Plan of Pierce-Arrow Motor Car Factory. 


Fig. 64—Exterior Elevation of Pierce-Arrow Body Building 


directly to the concrete by %-inch bolts bedded 
in the concrete. 


BODY BUILDING. 


The body Building, an exterior view of which 
is shown in Fig. 64, is a four-story structure, 
751 feet long and 140 feet wide, built with two 
wings 60 feet wide and a 40-foot open court be¬ 
tween them. It contains two large freight ele¬ 
vators, capable of handling the largest type of 
touring car, one smaller elevator and three rein¬ 
forced concrete stairways, each enclosed in iso¬ 
lated brick towers projecting out into the court. 

The beam and girder type 
of construction was used 
throughout the building, a 
single row of columns 25 feet 
on centers running through 
the center of the building. 

Fig. 67, illustrating the in¬ 
terior of the Wood-Working 
Room, is of particular inter¬ 
est as showing clearly the 
method of attaching the heavy 
motors direct to the ceiling 
and of suspending the shaft 
hangers, sprinkler pipes and 
electric-light fixtures from 
the concrete slab. 





































































































































74 





















































































Fig. 69—Interior View of Pierce-Arrow Engine Room. 


der to have a large unob¬ 
structed floor space, in which 
to move automobiles around 
easily, no interior columns 
were used in the building and 
the roof girders spanned 55 
feet so as to leave the entire 
floor clear. These girders are 
16 inches wide and 56 inches 
deep at center of the building, 
sloping with roof to 40 inches 
deep at wall columns. 

THE POWER HOUSE 
is a one-story structure, 55 
feet wide and 194 feet long, 
with no interior columns, the 
regular roof and monitor roof 
being carried by reinforced 
concrete girders spanning 55 
feet, see Fig. 69. 


75 












Fig. 70—Pacific Coast Borax Refinery. Designed and Built by Ernest L. Ransome, of Ransome & Smith Co. 


PACIFIC COAST BORAX REFINERY 


The distinction of being the designer and 
builder of the first two reinforced concrete fac¬ 
tory buildings in the world undoubtedly belongs 
to Mr. Ernest L. Ransome, of the Ransome & 
Smith Company. Of these the Pacific Coast 
Borax Refinery at Bayonne, N. J., a few miles 
from Jersey City, deserves special attention not 
only as one of the earliest examples of this type 
of construction, but for its notable record in 
passing through a terrific fire without structural 
injury. Moreover, the fact that it was not 
erected until 1897-8 serves to emphasize the 
marvelous growth in reinforced concrete con¬ 
struction. 

The time is so recent and reinforced concrete 
buildings are now so common that it is difficult 
to appreciate the boldness of the conception to 
construct a 4-story building, to sustain actual 
working loads of 400 pounds per square foot 
besides heavy machinery even on the top floor, 
out of a material until recently used almost ex¬ 
clusively for foundations, and considered capa¬ 
ble of resisting only compressive loads. Of 
course, the principle of steel reinforcement in 


concrete had been understood for a number of 
years previous to 1897. In fact, a house of re¬ 
inforced concrete was built in Port Chester,. 
N. Y., as early as 1871, and a few other similar 
structures appeared between this date and 1897. 
But with the exception of the factory at Ala¬ 
meda, Cal., also designed and built by Mr. Ran¬ 
some, the Pacific Coast Borax Building appears, 
to be, as above intimated, the first attempt at 
concrete factory construction. 

While it is not claimed that the design of 
this factory is in all respects typical of the up- 
to-date concrete factory building as now erected 
by the Ransome & Smith Company and other- 
contractors, many of its features and the meth¬ 
ods employed in its construction are well worth 
consideration. 

As built to-day, double walls are not regarded 
as essential for factories, but instead the wall 
surface is usually taken entirely by windows 
separated by concrete columns which support 
the floors above. In the floor system, slabs of 
longer span with correspondingly heavier beams 
are now more common, while expansion joints 


76 


















OsOiZ 














































































































































































































Fig. 73—Type of Wall Molds. 


in floors are not usually 
specified unless the building 
covers an extremely large 
area. 


DESIGN. 

The main building is 200 
feet long by 75 feet wide, 
and four stories high, ris¬ 
ing 70 feet above the 
ground. Connected with 
this and forming a part of 
it is a section which was 
built first only one story 
high, and then after the 
fire carried up to the full 
four stories, as shown in 
Fig. 70. The area of ground 
covered by the combined buildings is 50,000 
square feet. 

The plan of the first story is shown in Fig. 
72, the junction between the four-story and the 
one-story portion being indicated by the dot and 
dash line AA. In order to show the plan on a 
large scale, the first floor of the four-story build¬ 
ing is drawn in full and a part of the one-story 
portion is omitted as indicated by the irregular 
lines BB. 

The bays in general are 24 ft. 8% inches by 
12 ft. 4% inches; the columns in the first story 
are 21 inches square, in the second story 19 
inches, in the third story 17 inches, and in the 
fourth story 12 inches. They are computed by 
a maximum compression of 500 pounds per 
square inch. 

The sectional elevation in Fig. 71 shows the 
columns and also the column footings which are 
reinforced in the bottom with horizontal rods. 
The footings were designed so that the compres¬ 
sion upon the soil, which is of a marshy char¬ 
acter, should not exceed 2,500 pounds per square 
foot. 

Fig. 71 also illustrates the construction of the 
floor system, and, taken in connection with a 
plan of a portion of the second floor in Fig. 72, 
gives a good idea of the type of design. Gird¬ 
ers connect the columns which are 12 ft. 4% 
inches on centers. Between the girders and at 
right angles to them, run the concrete floor 
beams about 3 feet apart and so thin and deep 
that they resemble timber joists in appearance. 
As these beams are nearly 25 feet long in the 
clear, a stiffening web crosses them in the mid¬ 
dle, designed to serve the same purpose as bridge- 
ing in wooden floor joist construction, that is, to 


assist in preventing tendency to buckle under 
heavy loads. The girders are of rather peculiar 
construction, being made thicker in the panels 
next to the columns so as to save expense in 
forms. (See Fig. 71.) 

Originally, the columns in the fourth story of 
the main building and also the roof were of 
w r ood, while the one-story part was of similar 
construction. After the fire the wood was all 
replaced by concrete, as shown in the plans. The 
roofs were then built as reinforced slabs of 12 ft. 
4% inches span from centre to centre of the 
beams, the latter being 24 ft. 8% inches long be¬ 
tween column centres. Still later the roof of the 
low part formed the floor for the second story 
when this portion of the building was raised to 
full height, shown in the finished photograph, 
Fig. 70. 

The reinforcement of the beams and girders 
and stiffeners of the principal floors is shown 
at the lower part of the diagram, Fig. 71. The 
slabs were built of such short span that they 
received no reinforcement, the depth being 4 
inches in addition to the 1-inch cement finish. 

The floors with the beams and girders were 
laid as separate panels about 24 feet square, a 
vertical contraction being carried down through 
the beams on a line with alternate columns; that 
is, every eighth beam was built double. As stated 
above, it is not now customary to insert contrac¬ 
tion joints except on extraordinarily large sur¬ 
faces, the contraction being provided for instead 
by the steel reinforcement in the beams and 
slabs. 

The exterior walls were finished by picking 
the surface with a sharp tool which removed the 
outside skin of cement so as to show the stone and 


78 















































































mortar between and resemble 
pean hammered masonry. A 
part of this work was done by 
hand and part with pneumatic 
hammers. Although a pneu¬ 
matic hammer averaged about 
400 square feet in ten hours, 
while by hand 100 to 150 
square feet was a fair day’s 
work for a man, the actual 
cost with the power tool was 
but slightly less than by hand 
because of the higher grade 
of men required, the extra 
men for shifting air pipes, 
etc., and the wear and tear on 
the tools. 

The surface was also divid¬ 
ed into blocks by wood mold¬ 
ings nailed to the inside of the 
form. The stairs are also of Fig. 74—Photograph of Cast Iron Melted by the Fire 

reinforced concrete. 


CONSTRUCTION. 

Construction was begun late 
in the fall of 1897 and com¬ 
pleted in October, 1898. The 
usual time per story was 40 
to 50 days, whereas now such 
a building would be put up by 
the same builders at the rate 
of a story in one or two weeks. 

The column forms were 
built in the usual way with 
vertical boards paneled to¬ 
gether, and held with clamps 
surrounding them. The wall 
forms were %-inch dressed 
boards, designed in general 
like Fig. 73. 

These forms, patented by 
Mr. Ransome in 1885, are still 
extensively used in wall con¬ 
struction. The special fea¬ 
ture is the vertical standard made of two 1 by 
6-inch boards on edge with a slot between, 
through which pass the bolts. By loosening the 
nut, the plank behind the standards may be 
loosened and the standards raised. The walls 
were built in sections 4 feet high with central 
cores to form the hollow walls. 

White pine was used for forms, and the salvage 
on the lumber probably did not amount to more 
than 10 per cent, although by present methods 
the builders usually figure about 30 per cent. 

The total cost of the building was in the 


Fig. 75—Effect of Fire Upon Steel Tank House 


neighborhood of $100,000. 

THE FIRE 

Some four years after completion, in the spring 
of 1902, the Refinery was subjected to one of the 
most severe fires to which a manufacturing 
building is liable. Although the building itself is 
of concrete, it contained a large amount of wood 
in the form of partitions, window frames and 
bins, in addition to the wooden roof, and at the 
time of the fire one room happened to be com¬ 
pletely filled with empty wooden casks which pro- 


79 
















Fig. 76—View of Refinery After the Fire. 



Fig. 77—View of Refinery, Including New and Old Structures. 



















































































vided yet more fuel for the flames. Some of the 
material used in the manufacturing process was 
also extremely inflammable. 

To illustrate the heat of the fire, an insurance 
man called attention to the fact that the plank 
roof was entirely gone, with no charred wood re¬ 
maining, the brass in the dynamos was melted, 
and at least in one case a piece of cast iron was 
fused into a misshapen mass. A photograph of 
the melted cast iron is shown in Fig. 74. 

This fusing of the iron is especially remark¬ 
able since cast iron melts at the high temperature 
of about 2200° Fahr. The piece appears to be a 
portion of a pulley which was probably located 
near an opening in the floor through which there 
was a tremendous draft of flame. 

The chief structural damage to the building 
at the time of the fire was caused by the fall of 
an iron tank which was located on the wooden 
roof and supported by timbers from the fourth 
floor. This weight coming suddenly upon the 
floor broke the slab and two or three of the floor 
beams, but did not pass through to the floor be¬ 
low, being caught by the damaged floor. 

In several places throughout the building the 
concrete had been split off by the fire to a depth 
of 1/4 to 1 inch, and on one of the exterior walls 


a few cracks showed over a doorway. The total 
cost of repairs, including the portion of the floor 
broken by the tank, was in the neighborhood of 
$1,000. The broken beams were repaired by in¬ 
serting new concrete in the central portion and 
supporting it by bolts run down through the ends 
of the beams which still remained in place. 

As a result of the fire the structure was com¬ 
pletely gutted, nothing remaining but the rein¬ 
forced concrete and a mass of charred roof, with 
the machinery, shafting, dynamos, etc., melted or 
twisted out of shape. A photograph taken di¬ 
rectly after the disaster before any repairs were 
made is given in Fig. 76. This photograph also 
presents a very good view of the Refinery itself 
with the main building and the one-story addi¬ 
tion. 

In contrast with the durability of the rein¬ 
forced concrete under the action of the fire is a 
steel tank house adjoining the building. This 
was built with steel columns and roof girders, 
and the effect of the heat upon the steel struc¬ 
ture is graphically shown in Fig. 75, page 79. 

A photograph of the Refinery, taken in 1907 
and shown as Fig. 77, presents one view of the 
buildings, showing in the foreground the new 
part also built by Ransome & Smith and the 
older structure in the background. 


CHAPTER IV—DETAILS OF CONSTRUCTION 


To provide better adhesion or bond between 
the steel and concrete than is given by round or 
square rods, many types of deformed bars have 
been invented, and those most commonly used 
in the United States are illustrated in the pages 
which follow. Views are also shown of a num¬ 
ber of systems of assembling the steel or arrang¬ 
ing the reinforcement for application to special 
conditions. 

In addition to this digest of systems of rein¬ 
forcement, a number of photographs are pre¬ 
sented of details of construction most commonly 
met with in reinforced concrete buildings. In 
this connection are shown photographs of con¬ 
crete block walls, surface finish for concrete 
walls, concrete piles, and concrete tanks. 

SYSTEMS OF REINFORCEMENT. 

RANSOME TWISTED BARS.—One of the 
oldest types of reinforcing steel is the square 
twisted bar illustrated in Fig. 78, invented by 
Mr. E. L. Ransome, of the Ransome & Smith 
Co., and used as long ago as 1894. 

Twisted bars may be purchased ready to use, 
or on a large job may be twisted on the work. 
The number of twists per linear foot depends 
upon the diameter; thus, for 14 -inch bars there 
may be five twists per foot, and for 1-inch bars 
one twist per foot. 



Fig. 78—Ransome Twisted Bar. 


In computing cross-section area of steel in re¬ 
inforced concrete, the twisted bars are figured 
as square bars of the dimension before twisting. 
Twisted bars are employed in the Pacific Coast 
Borax Refinery and the Bullock Electric Com¬ 
pany shop, described on pages 76 to 81 and 45 
to 48. 

THACHER BAR.—The Thacher bar, Fig. 79, 
was designed and patented by Mr. Edwin 
Thacher, of the Concrete Steel Engineering 



Fig. 79—Thacher Bar. 

Company. Round bars are rerolled to the shape 
indicated. 

CORRUGATED BARS.—The corrugated bar, 
Figs. 80 and 81, is the invention of Mr. A. L. 
Johnson, of the Corrugated Bar Company. These 
bars are made in both square and round shapes 
and are rolled from billet stock, medium or high 
carbon steel. This company has devised a ma¬ 
chine fabricated beam and girder unit frame 
called Corr-Bar Units, Fig. 82, which is self- 



Fig. 80—Corrugated Square Bar. 


Fig. 81—Corrugated Round Bar. 

centering and collapsible. The normal size and 
net sections of both the round and square corru¬ 
gated bars are given in the following table: 


AREAS AND WEIGHTS OF CORRUGATED BARS. 
STANDARD SIZES 


8 











§ 

Size in inch¬ 










o 1 

es . 

M 

X 

X 

X 

X 

Vs 

1 

1 X 

IX 

m 

Net area in 









Id 

square 











inches... . 

.06 

.14 

.25 

.39 

.56 

.76 

1.00 

1.26 

1.55 

bJD 

P 

Weight per 











foot in 









0 

6 

pounds.. . 

.22 

.49 

.86 

1.35 

1.94 

2.64 

3.43 

4.34 

5.35 

-3 

c 

3 

Size in inches 

X 

X 

TS 

% 

X 

X 

1 

m 

IX 

0 

Net area in 










PH 

square 










T5 

<D 

inches.. . . 

.11 

.19 

.25 

.30 

.44 

.60 

.78 

.99 

1.22 

"5 

bfi 

Weight per 











foot in 










Sh 

O 

pounds.. . 

.38 

.66 

.86 

1.05 

1.52 

2.08 

2.69 

3.41 

4.21 

O 












82 




















DIAMOND BAR.—The diamond bar, Fig. 83, 
is one of the most recent types of rolled bar and 
the invention of Mr. William Mueser, of the Con- 



Fig. 82—Corr-Bar Units. 


Crete Steel Engineering Company. The sizes 
correspond to those of square bars, as shown in 
the following table: 



Fig. 83—Diamond Bar. 


Areas and Weights of Diamond Bars 


Size .. 


% in. 

% in. 

% in. 

% in. 

Area in 

square inches... 

.. .0625 

.1046 

.25 

.39 

Weight 

per foot. 

.213 

.478 

.85 

1.33 

Size .. 


% in. 

% in. 

1 in. 

1)4 in. 

Area in 

square inches 

.56 

.76 

1.00 

1.56 

Weight 

per foot. 

. 1.91 

2.60 

3.40 

5.31 


KAHN TRUSSED BAR.—The Kahn trussed 
bar, Fig. 84, invented by Mr. Julius Kahn, of the 
Trussed Concrete Steel Company, is rolled with 
flanges, which are bent up, as shown in the figure, 
to resist the shear in the beam. The Kahn bar 
is employed in the Packard building, described 
on pages 62-64. 



airr*rro 


Fig. 84—Kahn Trussed Bar. 

RIB BAR.—The rib bar, another product of 
the Trussed Concrete Steel Company, is rolled 
with four longitudinal ribs connected at frequent 
intervals by cross ribs, so as to form cup depres¬ 
sions between them designed to grip the concrete. 

Areas of cross-section of cup bars are made to 
correspond to square bars of the same nominal 
size. 

HAVEMEYER BARS.—The Havemeyer bar, 
Fig. 85, is the invention of Mr. J. F. Havemeyer, 



Fig. 85—Havemeyer Bar. 

of the Concrete Steel Company. It is rolled in 


both square and round shapes. The square bar 
has a series of projections and depressions in 
conjunction with the plain square section of the 
bar, the projections on the sides equaling the de¬ 
pressions on the corners. The round bar has 
projections staggered on alternate faces. Both 
the round and the square bars have the same net 
sectional area and the same gross weight as plain 
bars of the same nominal size. 

EXPANDED METAL.—One of the oldest 
forms of sheet reinforcement is expanded metal 
invented by Mr. John T. Golding. 

Sheet steel is slit in a special machine and 
then pulled out or expanded so as to form a dia¬ 
mond mesh. 


EXPANDED METAL MESHES 



Designation 

Section in 
Square 
Inches per 
Foot of 
Width 

Weight 

Mesh 

Gage 

(Stubs) 

Strand— 
Standard 
or Extra 

per 

Square 

Feet in 
Pounds 

y 2 in. 

No. 18 

Standard 

.209 

.74 

M in. 

No. 13 

Standard 

.225 

.80 

1)4 in. 

No. 12 

Standard 

.207 

.70 

2 in. 

No. 12 

Standard 

.166 

.56 

3 in. 

No. 16 

Standard 

.083 

.28 

3 in. 

No. 10 

Light 

.148 

.50 

3 in. 

No. 10 

Standard 

.178 

.60 

3 in. 

No. 10 

Heavy 

.267 

.90 

3 in. 

No. 10 

Extra 

Heavy 

.356 

1.20 


LATHING 


Designation 

Gage, 

United 

States 

Stand¬ 

ard 

Size 
of: 

Sheets 

Sheets 
in a 
Bundle 

Square 
Yards 
in a 
Bundle 

Weight 

per 

Square 

Yard 

A. 

24 

18 x96 

9 

12 

4)4 

Special B. 

27 

20Mx96 

9 

13)4 

2 % 

Diamond No. 24 

24 

22)4x96 

9 

15 

3 

Diamond No. 26 

26 

24 x96 

9 

16 

2 M 

Emco No. 24. . 

24 

27 x96 

9 

18 

3 

Emco No. 27. . 

27 

27 x96 

9 

18 

2)4 


83 






































Fig. 86—Laying Clinton Welded Wire in Decauville Garage, New York. 



Fig. 87—Triangle Mesh Reinforcement. 


CLINTON WELDED WIRE. 

—Clinton welded wire fabric, 
made by the Clinton Wire 
Cloth Company, is manufac¬ 
tured in different sizes of 
mesh and different gages of 
wire. As commonly made, the 
longitudinal strands are of 
larger diameter and closer 
spacing than the cross 
strands, the latter being 
chiefly to prevent construc¬ 
tion cracks in the concrete. 

The wires are electrically 
welded at every intersection. 

The fabric is furnished in 
diameters of wire ranging 
from y 10 inch to %o inch, and 
with spacing between the 
strands from 2 inches up to 
20 inches. 

The laying of the fabric in 
the Decauville garage, New 
York, is illustrated in Fig. 86. 

TRIANGLE MESH REIN¬ 
FORCEMENT. — Triangle 
mesh steel-wire reinforce¬ 
ment, Fig. 87, manufactured 
by the American Steel and 
Wire Company, is made with 
both single and stranded lon¬ 
gitudinal or tension members. 

That with the single-wire lon¬ 
gitudinal is made with one 
wire varying in size from a 
No. 12 gage up to and includ¬ 
ing a -inch diameter, and 
that with the stranded longi¬ 
tudinal is composed of two or 
three wires varying from No. 

12 gage up to and including 
No. 4 wires stranded or twist¬ 
ed together with a long lay. These longitudinals, 
either solid or stranded, are always spaced 4 
inches on centers, sizes being varied to obtain 
desired cross-sectional area of steel per foot of 
width. 



Fig. 88—Hy-Rib 

HY-RIB.—Hy-rib, illustrated in Fig. 88, and 


made by the Trussed Concrete Steel Company, 
consists of a steel sheathing with deep stiffening 
ribs for concrete and plaster work. It is a com¬ 
bined unit of reinforcement for centering studs 
and lath. 

TRUSSIT.—Trussit is formed by expanded 
metal or herringbone lath bent to V-shape sec¬ 
tion, as shown in Fig. 89. It is a self-centering 
reinforcement for light concrete roofs erected 
without forms, solid partitions, without stud¬ 
ding, curtain walls, fences, etc. It is manufac¬ 
tured by the General Fireproofing Company. 


84 















































FERROINCLAVE.—Ferro¬ 
inclave, invented by Mr. 
Alexander E. Brown, of the 
Brown Hoisting Machinery 
Company, is sheet metal bent 
as in Fig. 90, and spread over 
or plastered with mortar to 
form a sheet 1% inches thick. 

CUMMINGS SYSTEM. — 
A number of reinforcement 
details have been presented 
by Mr. Robert A. Cummings, 
as illustrated in Fig. 91. 

In the illustration at the 
top of the diagram is shown 
the Cummings method of 
forming the bent-up bars and 
attaching them to the tension 
bars. In general the plan is 
to provide tension bars with 
ends specially anchored, while 
securely attached to them are 
small rods horizontal in the 
middle of the beam or girder, 
or bent up, as indicated, to 
pass across the top of the 
beam and form inclined in¬ 
verted U bars or stirrups. 
The “Supporting Chair s,” 
placed at the point of the 
bending up of the rods, are 
also drawn. For the slab 
steel another type of support¬ 
ing chair is employed, as illus¬ 
trated in the detail sketch. 

HERRINGBONE GIRDER 
BAR AND FRAME.—The 
herringbone bar made by the 
General Fireproofing Com¬ 
pany consists of a main ten¬ 
sion member of either square 
or twisted, lug bars to which 
looped stirrups are rigidly at¬ 
tached. The bar is shipped 
from the shop completely as¬ 
sembled, so that the only work 
required in the field is the 
bending of the stirrups to the 
proper angle. When a girder 
frame is desired, it may be 
easily formed by inserting a 
properly bent bar through the 
loops and wiring it to shear 
members. 



Fig. 89—Trussit. 



Fig. 90—Placing of Ferroinclave Roof. 



85 
















































































Fig. 93—Concrete Block Walls, Salem Laundry. 



Fig. 94—Photograph of Spatter Dash Finish of Lynn Storage Warehouse. 


CONCRETE BLOCK WALLS. 

Frequently concrete blocks 
are cheaper for factory walls 
than solid concrete, because 
no forms are required. How¬ 
ever, if used in combination 
with reinforced concrete in¬ 
terior construction or with 
steel beams, they must be se¬ 
curely connected to them with 
ties, and the compressive 
strength of the blocks care¬ 
fully figured to see that there 
is sufficient area of concrete 
to carry the weight. 

In the warehouse at Nash¬ 
ville, pages 51-53, concrete 
blocks are utilized for parti¬ 
tions. 

An example of a concrete 
block exterior with a rein¬ 
forced concrete interior con¬ 
struction is shown in Fig. 93. 

This illustrates the Salem 
Laundry Building, Salem, 

Mass., of which Ballinger & 

Perrot were architects, and 
Simpson Brothers Corpora¬ 
tion, builders. This has a re¬ 
inforced concrete floor system 
and interior columns of solid 
concrete. The exterior col¬ 
umns are hollow blocks with 
reinforcing rods running 
through the openings in them 
and surrounded by mortar of 
the same proportions as the 
block themselves, so as to 
form solid piers. 

CONCRETE TILE. 

Concrete tiles are being used 
for partitions and floors the 
same way that terra-cotta tiles are employed. 
They are also coming into extensive use for the 
exterior walls of dwelling houses. They lay 
very true and even, and for the better class of 
buildings are plastered. 

One of the best patented processes for making 
concrete tile consists in pouring the wet con¬ 
crete of the consistency of grout into a mold and 
then, by means of a steam jacket, which forms a 
part of the mold, the water is evaporated from 
the concrete, so as to permit the withdrawal of 
the tiles from the molds within a few minutes. 
The product is thus as dense and uniform as wet 


mixed concrete and yet very true in ghape and 
size. Plastering adheres better than to most 
other forms of concrete. 

The factory of the Hunter Illuminated Car 
Sign Company, described on pages 49 to 50, is 
built of concrete hollow tile or, as it is termed, 
“Tilecrete,” manufactured, as described in the 
last paragraph, under the Pauly Process. In this 
building the tiles are laid up with mortar with¬ 
out any plastering on the surface. 

SURFACE FINISH. 

One of the most striking developments in re- 


86 
















Fig. 95—Tooling the Surface of Friedenwald Building Walls. 


Fig. 96—Photograph of Tooled Surface. 


inforced concrete industrial buildings has been 
the constant improvement in architectural de¬ 
sign and in the exterior and interior finish. While 
in factory construction the appearance of the 
building is usually of less consequence than in 
the case of office or public buildings, the effect 
should be pleasing to the eye. 

Plastering on solid concrete or on concrete 
blocks is unsatisfactory in climates where the 
temperature in the winter months falls below 
freezing. A very thin skin of cement may be 
plastered on by a skilled mechanic, but this 
is apt to appear streaked and prove unsatis¬ 


factory over a large surface. 
If the surface is broken by 
moldings or joints this plan 
can be used with fair results. 

A variation of this method 
is to float the concrete sur¬ 
faces with a sand-cement 
grout applied as soon as 
forms are removed. This is 
only valuable where the forms 
can be removed in one or two 
days after pouring. When 
this can be done the 1:1 grout 
is rubbed into the surface 
with a wood float. This is not 
a plastering method, but 
really is a rub finish; the 
grout serving to fill up the 
pores of the concrete. When 
concrete is too hard to be 
treated in this manner, satis¬ 
factory results may be ob¬ 
tained by using a carborun¬ 
dum brick instead of a float. 

Another style of finish is 
obtained by removing the wall 
forms within twenty-four 
hours and immediately wash¬ 
ing the surface. To do this 
satisfactorily the concrete 
cannot be laid very wet, or the 
water will run down over the 
completed surface. A similar 
effect is obtained with acid 
treatment. 

Another type of finish, 
which tests of several years 
in New England have shown 
to be satisfactory if properly 
applied, is the slap-dash, illus¬ 
trated in Fig. 94 (p. 86), 
which is a view of the wall of the Lynn storage 
warehouse built by the Eastern Expanded Metal 
Company, and described on pages 39 to 42. The 
wall is first plastered with cement mortar, and 
after drying the slap-dash is thrown on. 

An excellent finish, although a somewhat ex¬ 
pensive one, is obtained by removing the surface 
skin of cement which forms against the molds by 
dressing it with a pointed hammer of a pneu¬ 
matic tool. This method is illustrated in Fig. 95 
(above), and a photograph of the same wall, 
taken at close range, is shown in Fig. 96. 


87 

























y Wire rope for putting form. 

?ope dips. 
yPui/ing damps. 

Top of concrete F//ing. 



Cast Iron Point Driving Form. 

Operation Finished P/le. 



Alligator PointDrmng Form. 

Operation. Finished Pile. 


Standard Simplex Concrete Piles 


Fig. 97—Simplex Pile. 


CONCRETE PILE 
FOUNDATIONS. 

In certain cases concrete 
piles are an economical sub¬ 
stitute for wood piles or deep 
pier foundations. Where the 
loading is excessive or the 
durability of a wood pile is 
doubtful the use of concrete 
piles is an economy. Wood 
piles rot and deteriorate un¬ 
less there is sufficient water 
to keep them constantly wet. 

In sea water, wood piles are 
rapidly attacked by teredo 
worms, although this trouble 
does not often apply to fac¬ 
tory foundations. 

Two kinds of concrete piles 
are used: The cast-in-place 
pile and the pre-cast driven 
pile. In the first a hole is 
made in the ground by one 
method or another and the 
concrete cast in. In the sec¬ 
ond the pile is cast above the 
ground and afterward jetted 
or driven to position. Local 
conditions and considerations 
determine which type is used. 

Four types of patented rein¬ 
forced concrete piles are illus¬ 
trated in the following figures: 

The Simplex pile, manufac¬ 
tured by the Simplex Concrete 
Piling Company, is construct¬ 
ed by driving a hollow shell 
with a point to the full depth 
and filling the hole with con¬ 
crete as the shell is with¬ 
drawn. The different proc¬ 
esses used in driving this pile 
are shown in Fig. 97. 

The Raymond pile of the Raymond Concrete 
Pile Co. is formed as follows: A collapsible man¬ 
drel or core is expanded. This expanded core is 
encased in a sectional, spirally reinforced sheet 
steel shell. The combined core and shell is 
driven to sufficient penetration. The core is then 
collapsed and withdrawn from the shell. The 
shell—which remains in the ground—is then 
carefully inspected. Concrete is now poured into 
the shell. (See Fig. 98.) 

The corrugated pile, patented by Frank B. 
Gilbreth, Fig. 99 (p. 89), is cast on the ground 


and driven by a pile-driver with the aid of a 
water jet. The illustration shows a corrugated 1 
pile in process of driving for the foundation of 
the warehouse for Mr. John Williams, at West 
Twenty-seventh Street, New York City. 

The pedestal pile patented by the Mac Arthur 
Concrete Pile and Foundation Company, Fig. 109 
(p. 89), has an enlarged base providing a greater 
bearing. It is formed by first driving a core and’ 
cylindrical casing to the required depth. The 
core is then removed and a charge of concrete 
dumped to the bottom of the casing, the core- 
then being used as a rammer to compress this;. 


88 




















































89 












































Fig. 101—Hennebique Compressed Pile—See page 88. 


concrete into the surrounding soil until the base 
is about 3 feet in diameter, after which the cas¬ 
ing is filled to the top with wet concrete. After 
the pile is formed the cylindrical casing is with¬ 
drawn from the ground. 

The compressed pile of the Hennebique Con¬ 
struction Company, Fig. 101 (above), is formed 
by dropping a heavy steel-pointed weight so as 
to compress the soil laterally and vertically and 
then filling the resulting cavity with concrete. 
The concrete is tamped with a rammer, the final 
result being a supporting column larger at the 
base than at the top. 

DRIVEN PILES.—In cases where too many 
boulders are not liable to be encountered, piles 
are built upon the ground, reinforced with steel 
rods, and, after setting for at least a month, are 
driven with a pile driver. The corrugated pile, 
illustrated on page 89 (Fig. 99) and described 
on page 88, is a special form of driven pile. 

Where the foundation materials allow it, pre¬ 
cast piles are often driven by a combination of 
water-jetting and driving with a hammer. The 
water jet makes it possible to sink the pile to 
almost its final position and then with a few 
blows from the hammer to settle it into place. 

If the pile is to be jetted down the jet pipe is 
usually cast in the center of the pile, with the 
open end at the point of the pile. 

The piles used under the power house of the 
Boston Woven Hose and Rubber Company, and 
shown in Fig. 102 illustrate this type of driven 
pile and show the jet pipe in place. 



Fig. 102—Detail of Reinforced Concrete Pile, Boston 
Woven Hose & Rubber Co. 


90 
















































































Figure 103—Revere Rubber Company, Chelsea, Mass. Lockwood, Greene & Company, Architects & Engineers. 

Aberthaw Construction Company, Contractors 






























































































r T j 


|titro 

—J j 

i i 

- \ ^ 

gag] 

r li i 111 lil 


"a 


Figure 105—Goodell-Pratt Company, Greenfield, Mass. J. R. Worcester & Company, Architects & Engineers. 

Aberthaw Construction Company, Contractors 



Figure 106—General Electric Company Building No. 26, Fort Wayne, Ind. 
Harris & Richards, Architects. Wells Bros., Contractors 


92 

























































































Figure 107—'American Can Company, Brooklyn, N. Y. N. M. Loney, Engineer. Turner Construction Company, 

Contractors 



Fig. 108_A. Booth & Company, Detroit, Mich. John Scott & Company, Architects. Concrete Steel & Tile Con¬ 

struction Company, Contractors 

98 














































































































INDUSTRIAL PLANT ROADWAYS 


In addition to its use in the buildings of the 
plant, concrete has been put to efficient use in 
the construction of plant roadways. The neces¬ 
sity of a hard durable road leading to the plant 
and connecting its buildings is apparent. Every 
industrial organization must be planned to run 
365 days—and even nights—in the year in time 
of necessity, and its output must not be held 
down by poor roadways and transportation. 

Roadways that are always rutty and dusty 
and in wet or frosty weather almost impassable 
are not only wasting money, but often actually 
reduce the plant output through delays in receiv¬ 
ing and delivering materials. 

The phenomenal success of concrete for high¬ 
ways has caused the adoption of similar con¬ 
struction for plant roadways. The fact that con¬ 
crete offers a roadway that is hard and usable 
every day regardless of weather makes it the 
ideal material for the purpose. In addition, con¬ 
crete roadways are not dusty; can be cleaned by 
flushing with a hose; and, above all, require no 
extensive maintenance with its attendant vexa¬ 
tious obstructions to the operation of the plant. 

CONSTRUCTION DETAILS. 

The plant roadway of concrete is constructed 
in exactly the same way as a concrete country 
highway. The concrete is proportioned 1 part 
Portland cement to 2 parts sand to 3 parts broken 
stone. A very flat crown may be used owing to 
the superior drainage qualities of concrete. This 
crown is made a maximum of % 0 of the width of 
road or a minimum of y 100 the width. The thick¬ 


ness of roadway at sides ordinarily is 6 inches. 

Where a plant roadway has a building at each 
edge it is convenient to dish the surface so as to 
allow rain-water to drain down the center. Con¬ 
crete allows this to be done, and thus removes 
one of the chief causes of unsatisfactory service 
in a cinder, dirt or gravel road. 

PLANTS USING CONCRETE ROADWAYS 

A partial list of prominent corporations at 
whose plants concrete roadways have been built 
follows: 

S. S. White Dental Supply Co., Princess Bay, 
N. Y. 

Harrison Brothers & Co., Inc., Philadelphia. 

Studebaker Corporation, Detroit, Mich. 

American Can Company, Hackensack, N. J. 

Atlantic, Pacific & Gulf Co., Brooklyn, N. Y. 

E. I. du Pont de Nemours & Co., Hopewell, Va. 

E. I. du Pont de Nemours & Co., Harrisburg, 
Pa. 

Allis-Chalmers Co., West Allis, Wis. 

General Chemical Co., Edgewater, N. J. 

Henry Bower Chemical Mfg. Co., Philadelphia. 

American Dyewood Co., Chester, Pa. 

The Hess-Bright Mfg. Co., Philadelphia, Pa. 

Sherwin Williams Paint Co., Chicago. 

Continental Can Company, Chicago. 

Russel Wheel & Foundry Co., Detroit, Mich. 


Full specifications for concrete roads and 
alleys may be obtained by addressing The Atlas 
Portland Cement Co., 30 Broad St., New York, 
or Corn Exchange Bank Bldg., Chicago. 


94 











Old, Inefficient Roadway. New Concrete Roadway. 

Harrison Brothers & Co., Inc., Plant at Philadelphia, Pa. Atlas Portland Cement Used Exclusively. 
E. C. Thompson, Plant Supt.; J. R. A. Hagermans, Field Engineer; Henry E. Baton, Contractor 




Another View of Harrison Brothers & Co., Inc., Plant at Philadelphia, Showing Concrete Roadway 

----- 


Vi: 


Part of the System of Concrete Driveways and Walks at the General Chemical Co. Plant, Edgewater, N. J. 

95 



































I N presenting this book to you, we are of the 
full belief that it will be of real value. Be¬ 
low we show a comparative statement of 
relative values. These facts are all clearly 
brought out in the preceding pages. The 
question in your mind resolves itself into, 
whether you—as a prospective builder, archi¬ 
tect, or engineer—want a building. 


Firstly of: ■ 

Reinforced Concrete Construction, with 

Lowest final cost (all classes considered) 

Lowest insurance rate (all classes considered) 

Lower initial cost than steel construction 
Perfect Rigidity 
No depreciation, or repairs 
Unexcelled sanitary qualities 
Maximum Lighting 
Absolute Fireproofness 

Secondly: 

Steel Cage, Fireproofed, with— 

Highest initial and final cost (all classes considered) 
Medium insurance rate (all classes considered) 
Noticeable vibration 
Fair lighting 

Only fire resistive qualities 

Thirdly: 

Slow Burning, or Mill Construction, with— 

Low initial cost (all classes considered) 

High insurance rate (all classes considered) 

Vibration 

Marked depreciation 
Lighting difficulties 
No resistance to fire 

When you have decided by elimination, in favor of Re¬ 
inforced Concrete, take into consideration the recognized 
merit, the indisputable quality standard of 









<'w' 



LIBRARY OF CONGRESS 


0 033 266 447*5 



Reinforced Concrete Factory—The Carter’s Ink Company, Cambridge, Mass. 
Densmore LeClear, Architects Aberthaw Construction Co., Contractors 


“ The Standard by which all 
other makes are measured ” 









| 

































